T-Q, S-T segment mapping and hyperemia in reperfused pig heart with ischemic preconditioning.

The effects of ischemic preconditioning on epicardial T-Q and S-T segment mapping, local activation, and coronary blood flow were analyzed in nine barbiturate-anesthetized pigs during four coronary occlusion (5 min)-reperfusion (20 min) sequences. In seven sham pigs, one occlusion was performed after a control period of 75 min. The first reperfusion induced a marked coronary hyperemia [11 +/- 4 ml/min (baseline) to 33 +/- 16 ml/min, P < 0.005] and a rapid recovery (30 to 150 s) of epicardial activation delays, T-Q segment depression, and S-T segment elevation in the ischemia area. This recovery was transiently associated with enlargement of intersite T-Q potential variability (alpha: 2.5 +/- 0.6 to 3.4 +/- 0.7 mV, P < 0.05), T-Q segment overshoot to +1.4 +/- 0.9 mV, and S-T segment reelevation. A brief T-Q segment depression (-2.3 +/- 0.9 mV) occurred during early reperfusion in 60 of 91 electrodes overlying the normal myocardium. Compared with the first, the fourth occlusion induced lower S-T segment elevation (3.4 +/- 2.0 to 1.7 +/- 1.9 mV, P < 0.05), and the fourth reperfusion elicited a faster reversal of T-Q segment dispersion (53 +/- 21 to 43 +/- 16 s, P < 0.05), S-T segment elevation (149 +/- 101 to 81 +/- 45 s, P < 0.05), and coronary hyperemia (8 +/- 2 to 5 +/- 1 min, P < 0.05). This trend of changes was not observed during a fourth occlusion in sham pigs.(ABSTRACT TRUNCATED AT 250 WORDS)


Trophic effects of catecholamines and parathyroid hormone on adult ventricular cardiomyocytes.

Trophic effects of isoproterenol (Iso), norepinephrine (NE), phenylephrine (PE), and biologically active fragments of parathyroid hormone (PTH), PTH-(1-34) and PTH-(28-48), were investigated in mechanically quiescent, isolated ventricular cardiomyocytes from adult rat. In 24-h incubations in modified serum-free medium 199 incorporation of [14C]phenylalanine, changes in total protein and specific activities of cytosolic enzymes, creatine kinase (CK) and lactate dehydrogenase (LDH) were monitored. NE and PE (10 microM), but not Iso, distinctly increased phenylalanine incorporation, total cell protein, and specific activity of CK but not LDH. Induction of CK, but not LDH, was also produced by phorbol 12-myristate 13-acetate (10 nM) but not dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP, 1 mM). It was abolished by copresence of cycloheximide (35 microM) or actinomycin D (5 microM). CK-BB was the only induced isoform of CK, as shown for PE incubations. PTH-(1-34) and PTH-(28-48) (30-300 nM) had effects comparable to NE and PE. They increased phenylalanine incorporation and total protein content and induced CK but not LDH. In summary, distinct trophic effects on adult cardiomyocytes were found with alpha 1-adrenergic agonists, fragments of PTH containing the midregional amino acids 28-34, and direct activation of protein kinase C but neither beta-adrenergic agonists nor DBcAMP.


Differences in rate dependence of transient outward current in rabbit and human atrium.

Both human and rabbit atrial cells possess a large 4-aminopyridine-sensitive transient outward current (I(to1)). However, the slow reactivation of this current in rabbits suggests that its role may be limited to very slow heart rates. We used whole cell voltage-clamp recordings to evaluate the rate dependency of I(to1) in rabbit and human atrial myocytes. Our results show that at physiological temperatures in human atrium, I(to1) is rate independent at rates between 0.1 and 4.0 Hz. Peak I(to1) at 4.0 Hz in rabbit was 3.4 +/- 1.4% (mean +/- SE) of current at 0.1 Hz (P < 0.001, n = 8), whereas in humans, peak I(to1) at 4.0 Hz averaged 88.8 +/- 6.1% of the current at 0.1 Hz (P > 0.05, n = 7). These differences were due to marked discrepancies in reactivation time course, which was biexponential with time constants that averaged 650 +/- 159 ms and 8.4 +/- 1.1 s in rabbit (n = 8) compared with a single exponential time constant of 33.6 +/- 6.8 ms (n = 8) in human atrium (both at 30 degrees C). These findings suggest that I(to1) can contribute importantly to atrial repolarization at all physiological heart rates in humans. Furthermore, these results emphasize that there are important interspecies variations in the rate dependence of I(to1), which need to be considered in understanding the physiological and pharmacological regulation of atrial repolarization.


Pregnancy reduces serotonin-induced contraction of guinea pig uterine and carotid arteries.

Because platelet activation and serotonin have been implicated in preeclamptic hypertension, we investigated the effect of pregnancy on the contractile response to this agent. Prior studies have shown that the vascular contractions to norepinephrine, angiotensin II, and thromboxane are reduced during normal pregnancy by the altered release of endothelium-derived vasoactive substances. We hypothesized that the contraction to serotonin would also be reduced during pregnancy by an endothelium-dependent mechanism. Isolated ring segments from uterine and carotid arteries of near-term pregnant and nonpregnant guinea pigs were studied after stimulating a small amount of active tone with prostaglandin F2 alpha. Serotonin (10(-8) to 10(-5) M) contractile responses of both arteries were reduced by pregnancy. Regardless of pregnancy status, the contractile responses of the uterine artery to serotonin were severalfold greater than that of the carotid artery whose maximum averaged only 10% of the 120 mM KCl contraction. Denudation of uterine artery abolished acetylcholine-stimulated relaxation in vessels from pregnant and nonpregnant animals. However, serotonin-induced contractions were enhanced by denudation only in ring segments obtained from pregnant animals. Nitric oxide synthase inhibition by either NG-monomethyl-L-arginine (L-NMMA) or N omega-nitro-L-arginine and cyclooxygenase inhibition by indomethacin had no effect on serotonin-induced contraction of intact uterine artery regardless of pregnancy. L-NMMA modestly enhanced the intact carotid arterial response to 10(-5) M serotonin independent of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)


Blood viscosity in tube flow: dependence on diameter and hematocrit.

Since the original publications by Martini et al. (Dtsch. Arch. Klin. Med. 169: 212-222, 1930) and Fahraeus and Lindqvist (Am. J. Physiol. 96: 562-568, 1931), it has been known that the relative apparent viscosity of blood in tube flow depends on tube diameter. Quantitative descriptions of this effect and of the dependence of blood viscosity on hematocrit in the different diameter tubes are required for the development of hydrodynamic models of blood flow through the microcirculation. The present study provides a comprehensive data base for the description of relative apparent blood viscosity as a function of tube diameter and hematocrit. Data available from the literature are compiled, and new experimental data obtained in a capillary viscometer are presented. The combined data base comprises measurements at high shear rates (u > or = 50 s-1) in tubes with diameters ranging from 3.3 to 1,978 microns at hematocrits of up to 0.9. If corrected for differences in suspending medium viscosity and temperature, the data show remarkable agreement. Empirical fitting equations predicting relative apparent blood viscosity from tube diameter and hematocrit are presented. A pronounced change in the hematocrit dependence of relative viscosity is observed in a range of tube diameters in which viscosity is minimal. While a linear hematocrit-viscosity relationship is found in tubes of < or = 6 microns, an overproportional increase of viscosity with hematocrit prevails in tubes of > or = 9 microns. This is interpreted to reflect the hematocrit-dependent transition from single- to multifile arrangement of cells in flow.


Myocardial performance of STZ-diabetic DOCA-hypertensive rats.

Myocardial performance of streptozotocin (STZ)-diabetic deoxycorticosterone acetate (DOCA)-hypertensive rats was examined using the isolated working heart apparatus at various time periods after induction of the experimental diseases. Blood pressure, pulse rate, and plasma levels of glucose, insulin, cholesterol, and triglycerides, as well as ventricular weight-to-body weight ratio, were also determined. In nondiabetic rats it was found that DOCA hypertension was associated with an increase in plasma cholesterol, a decrease in circulating insulin level, lower weight gain, and ventricular enlargement compared with control rats. Diabetic rats developed myocardial dysfunction in a time-dependent manner and exhibited hyperglycemia, hypoinsulinemia, bradycardia, and ventricular enlargement. Compared with the normotensive diabetic animals, STZ-diabetic DOCA-hypertensive rats showed a similar magnitude of myocardial dysfunction and a greater degree of ventricular enlargement, but significantly less severe hyperglycemia. It is concluded that DOCA-induced hypertension does not aggravate the severity of myocardial dysfunction developed in STZ-diabetic rats. It is also suggested that DOCA may have an action on glucose metabolism either directly or via an effect on insulin secretion.


Acute endoneurial ischemia induced by epineurial endothelin in the rat sciatic nerve.

Endothelin (ET) is a potent vasoconstrictor peptide that may have pathophysiological roles in the microcirculation of the peripheral nervous system. We examined the local action of epineurial ET-1 on sciatic endoneurial blood flow using serial hydrogen clearance measurements in anesthetized, paralyzed, and ventilated Sprague-Dawley rats. In separate rats, we made serial measurements of sciatic motor multifiber conduction before and then after application of epineurial ET (saline on contralateral nerve) 2 and 24 h and 4 and 7 days later. Epineurial bathing solutions of ET increased microvascular resistance and reduced local endoneurial blood flow in a dose-responsive fashion with a half-maximum effective concentration of 10(-8) M. Maximum vasoconstriction at 10(-6) M ET was associated with a fall in endoneurial blood flow from 18.7 (pre-ET) to 7.2 ml x 100 g-1 x min-1. Epineurial norepinephrine (10(-7) to 10(-10) M) also resulted in vasoconstriction, but of lesser degree. Pretreatment with intraperitoneal nimodipine, a dihydropyridine Ca2+ channel antagonist, but not phentolamine, prevented the vasoconstrictive action of ET. Three of eight animals developed temporary but complete axonal conduction block at the site of ET administration (10(-5) M) and four others had partial conduction block. Contralateral saline-treated sciatic fibers were unaffected. Local ET action on extrinsic epineurial microvessels results in reversible ischemia of the underlying endoneurium that may be associated with conduction block. ET's action is more potent than norepinephrine and appears dependent on L-type voltage-gated Ca2+ channels.


2,3-Butanedione monoxime increases contractile efficiency in the rabbit ventricle.

The efficiency of chemomechanical energy transduction (contractile efficiency) of the left ventricle (LV) has been calculated from the linear correlation of the systolic pressure-volume area (PVA) of the LV and its O2 consumption (VO2). Thus far, a wide range of acute interventions, including adrenergic agents, Ca(2+)-sensitizing drugs, and Ca2+ channel blockers have not altered contractile efficiency. In contrast, hyperthyroidism has been reported to decrease contractile efficiency, an effect attributed at the cross-bridge level to an increase in the V1/V3 myosin isoenzyme ratio. We hypothesized that an acute intervention which directly alters cross-bridge cycling would also change contractile efficiency. Accordingly, 2,3-butanedione monoxime (BDM), a negative inotropic agent that is thought to directly inhibit cross-bridge formation, was administered to seven excised, red blood cell-perfused, isovolumically beating rabbit LVs. At 3-4 mM perfusate concentration, BDM resulted in the following reversible mechanical and energetic effects compared with control. Contractility, assessed by the slope (Emax) of the end-systolic pressure-volume relation, decreased by 11% (196.6 +/- 25.9 vs. 222 +/- 28 mmHg/ml). Both the time to end systole (Tmax) and relaxation half time (T1/2) decreased. The slope of the VO2-PVA relation decreased by 20% (1.55 +/- 0.44 x 10(-5) vs. 1.95 +/- 0.52 x 10(-5) ml O2 x mmHg-1 x ml-1), equivalent to an increase in contractile efficiency from 36.5 +/- 10.4 to 46.4 +/- 14.4%, while the O2 costs of the mechanically unloaded LV decreased by 12% (0.0258 +/- 0.0060 vs. 0.0292 +/- 0.0064 ml O2 x beat-1 x 100 g-1). Finally, BDM also produced coronary vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)


Ontogeny of baroreflex control of renal sympathetic nerve activity and heart rate.

The purpose of this study was to characterize the developmental changes in baroreflex function during fetal and postnatal life in sheep. Resting mean arterial blood pressure increased significantly from 55 +/- 2 mmHg in fetuses to 86 +/- 3 mmHg in newborn lambs and to 105 +/- 4 mmHg in 4- to 6-wk-old lambs. The sensitivity (gain) of the renal sympathetic nerve activity (RSNA) response to baroreceptor stimulation was greater (P < 0.05) in fetuses (-7.7 +/- 1.9%/mmHg) than in newborn (-2.9 +/- 0.1%/mmHg) and 4- to 6-wk-old lambs (-2.2 +/- 0.2%/mmHg). The threshold and saturation pressures for the baroreflex function curve were lower (P < 0.05) in fetuses (44 +/- 2 and 61 +/- 2 mmHg) than in newborn (59 +/- 4 and 106 +/- 5 mmHg) or 4- to 6-wk-old lambs (78 +/- 5 and 132 +/- 6 mmHg). Similar findings were observed when the heart rate response to baroreceptor stimulation was examined. Additional experiments were performed in newborn and 4- to 6-wk-old lambs to determine whether the rise in arterial blood pressure associated with postnatal maturation contributed to baroreflex resetting. Sustained elevation of arterial blood pressure by 15-20 mmHg for over 90 min did not reset the baroreflex function curve in either newborn or 4- to 6-wk-old lambs.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of hypoxia, hyperoxia and hypercapnia on graded cerebral ischemic responses in rabbits.

This study was designed to determine how several factors interact to modify the cerebral ischemic pressor response (CIR) in anesthetized rabbits. After the carotid sinus and aortic nerves were bilaterally sectioned, blood flow through the left internal carotid artery (ICF), which was surgically restricted as the sole route of blood supply to the brain, was reduced by a servo-controller during ventilation with room air, and 8% and 90% O2 and 2 and 5% CO2 gas mixtures. Blood flow (MBF), tissue PO2, PCO2, and interstitial pH were measured in the rostral ventrolateral medulla. Internal carotid arterial pressure, tissue PO2, and MBF decreased proportionately as ICF decreased in the range from 4 to 0 ml/min. Hypoxia significantly increased the rise in renal nerve activity (RNA) and CIR caused by cerebral ischemia, while hyperoxia significantly decreased them. Hypercapnia had almost no influence on the increases in RNA and mean arterial pressure produced by cerebral ischemia. CIR showed a much higher correlation with changes in tissue PO2 than with the other factors. We examined how these factors interact to modify CIR and found that central hypoxia is the main factor in producing CIR.


Skeletal muscle arteriolar constriction to ANG II: evaluation of a myogenic component.

This study addressed the hypothesis that an increase in blood pressure contributes to the overall constrictive response of skeletal muscle arterioles to angiotensin II (ANG II). Diameters of second-order arterioles (2A) and third-order arterioles (3A) in the rat cremaster muscle were quantitated after intravenous administration of ANG II. Hindquarter blood pressure was either allowed to increase or was maintained at normal levels. Constriction of 3A to bolus injection of ANG II was the same whether hindquarter pressure increased or not. However, the total vascular constrictive response of the cremaster muscle (based on 2A blood flow) and of the entire hindquarter (based on iliac arterial blood flow) to bolus ANG II was greater when hindquarter pressure was held constant. During slow infusion of ANG II, 3A constriction was unaffected by an abrupt decrease or increase in hindquarter pressure. However, an abrupt reduction of hindquarter pressure caused a significant decline in hindquarter vascular resistance. Thus an increase in blood pressure, whether rapid or gradual, does not influence 3A constriction to ANG II. However, in the entire hindquarter, a rapid rise in blood pressure opposes constriction to ANG II, whereas a gradual pressure rise evokes a mechanism that enhances constrictive response to the peptide.


Cellular Vmax reflects both membrane properties and the load presented by adjoining cells.

This study was designed to test the hypothesis that the electrical load seen at a microelectrode impalement site is sensitive to the direction of propagation of the approaching wavefront as a reflection of an altered spatial relationship between the impalement site and the surrounding microscopic electrical boundaries located up- and downstream. These boundaries correspond to the different sizes and shapes of the impaled and surrounding cells as well as to the distribution of the associated electrical connections between the cells. The effects of changes in these geometric relationships on maximum rate of rise of transmembrane potential (Vmax) were investigated in canine ventricular muscle by measuring Vmax in different cells while the direction of propagation was changed from along the longitudinal axis to the transverse axis of the fibers or the direction of conduction was reversed along either of these axes. Comparison of the Vmax values for longitudinal propagation (LP) and transverse propagation (TP), each in one direction, showed that TP Vmax was significantly greater than LP Vmax (P < 0.001). However, the values of Vmax were different from cell to cell during LP (93-139 V/s) and TP (110-181 V/s). The absolute values of LP Vmax and TP Vmax at the same site varied independently of each other, e.g., some of the lowest LP Vmax values occurred at the same site as the highest TP Vmax values. Furthermore, at the same site, Vmax changed considerably when propagation was maintained along the longitudinal axis but the direction of conduction was reversed. Similar prominent changes in Vmax occurred when the direction was reversed along the transverse axis.(ABSTRACT TRUNCATED AT 250 WORDS)


Hypocapnic-hypoglycemic interactions on cerebral high-energy phosphates and pH in dogs.

With a level of hypoglycemia (1-1.5 mM) that does not alter cerebral O2 uptake and glucose uptake in dogs, induction of hypocapnia may cause severe electroencephalographic (EEG) abnormalities. The aim of this study was to determine the effect of hypoglycemia (blood glucose = 1.1 +/- 0.1 mM) and hypocapnia (arterial PCO2 = 15 +/- 1 mmHg) on cerebral ATP, phosphocreatine, and intracellular pH (pHi; 31P magnetic resonance spectroscopy), cerebral blood flow (CBF; radiolabeled microspheres), global O2 uptake, and glucose uptake in anesthetized dogs. Neither hypoglycemia nor hypocapnia alone altered brain high-energy phosphates, pHi, O2 or glucose uptake or caused major EEG abnormalities. Hypocapnia alone decreased CBF to 62 +/- 4% of control. The combination of hypoglycemia and hypocapnia did not decrease CBF (85 +/- 6% of control), and O2 and glucose uptake were unchanged. During hypocapnic hypoglycemia, isoelectric EEG was seen in 40% of animals, ATP and phosphocreatine decreased to 38 +/- 12 and 43 +/- 12% of control, respectively, while pHi increased from 7.13 +/- 0.05 to 7.43 +/- 0.09. The increase in pHi was related reciprocally to the decrease in venous PCO2, indicating little change in intracellular bicarbonate concentration ([HCO3-]i). With normoglycemic hypocapnia, in contrast, estimated [HCO3-]i decreased 57 +/- 1%. These data suggest that active regulation of pHi during normoglycemic hypocapnia is impaired during hypoglycemic hypocapnia associated with decreased ATP.


Antibodies to SPARC inhibit albumin binding to SPARC, gp60, and microvascular endothelium.

Albumin, through its binding to the endothelial glycocalyx, functions as a major determinant of capillary permeability and as a carrier for various small molecules in its transcytosis across continuous endothelium via plasma-lemmal vesicles. Several albumin-binding proteins (ABP) have been identified: three membrane-associated ABP, which we call gp60, gp30, and gp18, and one secreted protein, acidic and rich in cysteine (SPARC). In this study, we used antiserum raised against bovine SPARC (BON) to investigate the possible interrelationships among ABP to better understand their role in binding and transcytosis. BON not only interacted with SPARC secreted by cultured endothelium but also recognized gp60 in lysates of cultured rat, human, and bovine endothelial cells. Purified SPARC inhibited BON interaction with gp60. BON immunoglobulin (Ig)G specifically inhibited albumin binding to both SPARC and gp60 extracts. This effect was eliminated by preabsorption of BON to immobilized SPARC. BON also significantly inhibited albumin binding to cultured microvascular endothelial cells via its interaction with gp60. Anti-SPARC peptide sera were also tested, and one serum raised against a peptide encompassing an NH2-terminal region of SPARC recognized both SPARC and gp60 but did not inhibit albumin binding; gp30 and gp18 were not recognized by any of these anti-SPARC antibodies. These results suggest that SPARC and gp60 are functionally and immunologically related ABP that may share a common albumin-binding domain. gp60 appears to be the major mediator of albumin binding to microvascular endothelium.


Role of endothelial cells in regulating hemoglobin-induced changes in lymphatic pumping.

Studies with a sheep isolated duct preparation in vivo demonstrated that the route of administration of hemoglobin was important in demonstrating its inhibitory effect on lymphatic pumping. With autologous oxyhemoglobin administered intravenously (final plasma concentration 5 x 10(-5) M), pumping was not inhibited. However, the addition of oxyhemoglobin (5 x 10(-5) M) into the reservoir (lumen of the duct) resulted in > 95% inhibition of pumping. The extraluminal administration of oxyhemoglobin (10(-5) M) to bovine mesenteric lymphatics in vitro resulted in a 40% inhibition of pumping, whereas the introduction of oxyhemoglobin (10(-5) M) into the lumen of the vessels suppressed pumping 95%. In vessels mechanically denuded of endothelium, intraluminal oxyhemoglobin inhibited pumping 50%. These results suggested that oxyhemoglobin depressed pumping through an effect on both smooth muscle and endothelium. Once pumping was inhibited with oxyhemoglobin administration, stimulation of the duct with elevations in transmural pressure restored pumping activity when endothelial cells were present. However, in the absence of endothelium, pumping decreased with increases in distending pressures. We conclude that oxyhemoglobin has a direct inhibitory effect on lymphatic smooth muscle. The ability of oxyhemoglobin to alter the pressure range over which the lymph pump operates appears to be dependent on an intact endothelium.


Microvascular ischemia-reperfusion injury in striated muscle: significance of "no reflow".

"No reflow" has been implicated as prominent phenomenon in microvascular injury associated with ischemia-reperfusion (I/R). The objectives of this study were 1) to elucidate the significance of no reflow in microvascular I/R injury of striated muscle and 2) to determine whether reactive oxygen metabolites play a role in the development of postischemic no reflow. By use of the hamster dorsal skinfold preparation and intravital microscopy, microvascular perfusion of capillaries and postcapillary venules of striated muscle was quantitatively assessed before and 30 min, 2 h, and 24 h after 4 h of tourniquet-induced ischemia. I/R was characterized by a significant reduction (P < 0.01) in functional capillary density to 35% of baseline values during initial reperfusion, with incomplete recovery after 24 h (n = 9). In addition, capillary perfusion was found to be extremely heterogeneous, and wall shear rate in postcapillary venules was significantly decreased (P < 0.01). Treatment with either superoxide dismutase (SOD; n = 9) or allopurinol (n = 9) resulted in maintenance of capillary density of 60% of baseline (P < 0.05). Furthermore, I/R-induced capillary perfusion inhomogeneities and decrease of wall shear rate in venules were attenuated significantly (P < 0.01) by SOD and allopurinol. Thus part of capillary perfusion disturbances during I/R in striated muscle may be caused by increased postcapillary vascular resistance, probably mediated by reactive oxygen metabolites. However, the fact that in SOD- and allopurinol-treated animals 40% of the capillaries were still found to be nonperfused indicates that mechanisms other than oxygen radicals play an important role in the development of postischemic no reflow.


Systemic hemodynamics and oxygen transport during pregnancy in chronically instrumented, conscious rats.

Knowledge about possible alterations in cardiac output (CO), total peripheral vascular resistance (TPVR), and their time course and magnitude of change is conspicuously lacking for the conscious gravid rat. Therefore, we assessed CO using Fick methodology in unrestrained, chronically instrumented, conscious rats. The rats were studied during early (day 7), mid (day 13), or late gestation (day 18) along with nonpregnant control rats matched with respect to age and days postsurgery. Significant differences between pregnant and nonpregnant rats were observed during midgestation, when CO was increased by 26 +/- 12% and TPVR was decreased by 23 +/- 9% in the pregnant animals. These changes were accompanied by a narrowed arterial-mixed venous oxygen content difference (AVD; P < 0.05 vs. nonpregnant). In late gravid rats, CO was higher than nonpregnant values by 49 +/- 8%, and TPVR was lower by 34 +/- 7% (both P < 0.05). Oxygen consumption and carbon dioxide production were significantly increased, and AVD further narrowed when compared with the nonpregnant control group. With the exception of absent chronic respiratory alkalosis in pregnant rats, we conclude that cardiovascular and respiratory changes in conscious, gravid rats and in pregnant women are comparable. We speculate that the ultimate purpose of many of these adaptations is to increase CO so that oxygen delivery and the supply of nutrients to the uteroplacental units are sufficient or more than sufficient to meet oxygen and nutrient demands. At midgestation, the rise in CO seems to anticipate the oxygen needs of the nascent uteroplacental units.


Evaluation of hypercholesterol diet-induced changes in viscoelastic properties of carotid circulation in pigs.

Measurements of pulsatile pressure and flow at the input of the left and right carotid arteries and a new lumped parameter model were used to quantify changes in the overall dynamic mechanical properties of the carotid circulation between five control diet-fed pigs and five pigs fed a hyperlipidemic diet for 16 wk. The model represents the portion of the circulation supplied by either the left or the right carotid artery and is characterized by five parameters: peripheral resistance (Rp), an overall inertance (L), and an overall frequency-dependent compliance constituted by a capacitor C (static compliance) in series with a Maxwell section, i.e., a capacitor Cd, in parallel with a resistor Rd. Rp was calculated as the ratio between mean pressure (P) and mean flow (Q). The other four parameters were estimated by fitting measured to model predicted flows. The average static compliance was reduced by 40% (P = 0.01) between normal (P = 62.0 +/- 4.3 mmHg) and hyperlipidemic diet-fed pigs (P = 62.7 +/- 4.7 mmHg). A significant reduction in the overall cross-sectional area was inferred from a 53% increase (P = 0.05) in L, whereas resistance vessel tone was unchanged as judged from estimates of Rp. No signs of occlusive disease were found in any of the animals.


Blood volume changes in microcirculation of rat intestine caused by carotid sinus baroreceptor reflex.

This series of experiments quantified the role of the rat small intestinal arterioles in capacity changes during bilateral carotid occlusion (BCO) and compared them with previous venular studies. We also determined the role of autoregulation in arteriolar constriction during BCO. First-order, second-order, and third-order arteriolar diameter changes were measured during changes in arteriolar pressure and/or sympathetic activity (via BCO). The results indicated that an arteriolar pressure drop caused an immediate significant transient diameter decrease of 14% (P < 0.001), followed by an average steady-state diameter increase of 11% (P < 0.001) over control because of autoregulation. During BCO, the arterioles demonstrated an initial 8-22% decrease in diameter (P < 0.05). The largest first-order vessels were the least responsive to changes in pressure and BCO, while the smallest third-order vessels were the most responsive. Apparently autoregulation, and not sympathetic activity, was responsible for most of the arteriolar constriction during BCO. We also developed an anatomic model of the rat intestinal vasculature which revealed that venules hold 70% of the microcirculatory volume and are responsible for 80% of the total blood shift during BCO. Venular constriction and, to a minor degree, arteriolar constriction result in a 14% decrease in microcirculatory intestinal blood volume during BCO.


New nonradioactive microspheres and more sensitive X-ray fluorescence to measure regional blood flow.

We developed new nonradioactive microspheres and used more sensitive X-ray fluorescence spectrometers than used previously to measure regional blood flow in the heart and other organs. We demonstrated the chemical stability of eight kinds of heavy element-loaded microspheres and validated their use for regional blood flow measurement by comparing duplicate flows measured with radioactive and/or nonradioactive microspheres in both acute and chronic dog experiments. The wavelength-dispersive spectrometer (Philips PW 1480) has a higher sensitivity than the previously described X-ray fluorescent system and reduced the number of microspheres required for accurate measurement. The fine energy resolution of this system makes it possible to increase the numbers of different kinds of microspheres to be quantitated, but at present only eight kinds are available. We also used a synchrotron radiation-excited energy dispersive spectrometer. The monochromatic synchrotron radiation allowed us to obtain much higher signal-to-background ratios of X-ray fluorescence spectra than with the wavelength-dispersive system (50 dB more for Zr-loaded microspheres) and will enable analysis of fluorescent activity in smaller regions (< 20 mg) than the radioactive method does.


Determination of chloride potential in perfused rat hearts by nuclear magnetic resonance spectroscopy.

Isolated beating rat hearts were perfused with trifluoroacetamide (TFM) and trifluoroacetate (TFA) and monitored by 19F-nuclear magnetic resonance (NMR). The average membrane TFA potential in spontaneously beating rat hearts, calculated according to standard principles assuming that TFA is distributed in its anionic form, was found to be -36.2 +/- 3.2 mV (n = 9) under normoxic conditions. In separate experiments, the chloride and potassium potentials were determined to be -38.5 +/- 3.6 mV (n = 7) and -85.3 +/- 3.3 mV (n = 7), respectively, from freeze-clamped heart tissue. In the presence of the anion-exchange inhibitor, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS), TFA uptake into heart was significantly reduced, suggesting that TFA uptake occurs partly via the Cl(-)-HCO3- exchanger. Based on these results and the results of R. E. London and S. A. Gabel (Biochemistry 28: 2378-2382, 1989), we conclude that the distribution of TFA in hearts reflects the chloride potential (ECl) and not the membrane potential. A time-dependent change in the ECl occurs during global ischemia, and changes in ECl were also observed when the hearts were perfused with high concentrations of KCl. These results demonstrate that 19F-NMR may be utilized to monitor the ECl of perfused hearts under a variety of conditions.


Nitric oxide production within cardiac myocytes reduces their contractility in endotoxemia.

We investigated whether increased nitric oxide (NO) synthase activity within cardiac myocytes contributes to the depressed cardiac contractility observed in endotoxic shock. Isolated ventricular myocytes were studied to examine the effects of substrates and inhibitors of NO synthase on myocyte contractility. When stimulated electrically, the resting length of myocytes from control animals shortened by 5.3 +/- 0.3% (means +/- SE, n = 32). Baseline contraction of myocytes from endotoxin-treated animals was reduced to 3.0 +/- 0.3% (n = 17, P < 0.001). The NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 10(-4) M) had no effect on myocytes from control animals, but it increased the contraction of myocytes from endotoxin-treated animals by 40% (fractional shortening increased to 4.3 +/- 0.4%, P < 0.01). Similar results were obtained with NG-methyl-L-arginine. The effect of L-NAME could be reversed by excess L-arginine, but not D-arginine. The effect of endotoxin was abolished by dexamethasone pretreatment. Methylene blue also reversed the effects of endotoxin but had toxic effects on myocytes. Agents that either prevent synthesis or the effects of NO reverse the depression of myocyte contraction seen following endotoxin treatment.


Sustained outward current observed after I(to1) inactivation in rabbit atrial myocytes is a novel Cl- current.

In rabbit atrial myocytes, depolarization of the membrane results in a rapidly activating transient outward current (I(to)) that then decays to a sustained level. The sustained current (Isus) remains constant for at least 5 s during continued depolarization. The present study was designed to identify the ionic mechanism underlying Isus with the use of whole cell voltage-clamp techniques. After exposure to 2 mM 4-aminopyridine (4-AP), the 4-AP-sensitive transient outward current (I(to1)) was abolished, but Isus was unaffected. Isus was not blocked by the K+ channel blockers tetraethylammonium chloride and Ba2+, was not changed by increasing superfusate K+ concentration, and was still present when K+ was replaced by Cs+ in both the superfusate and the pipette. Isus was significantly reduced by the Cl- transport blockers 4-acetamido-4'-isothiocyanatostilbene-2.2'-disulfonic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. The current-voltage relations of Isus showed outward rectification, and the reversal potential of Isus shifted with changes in the transmembrane Cl- gradient in the fashion expected for a Cl- current. We conclude that Isus in rabbit atrium is due to a noninactivating Cl- current which, unlike previously described cardiac Cl- currents, is manifest in the absence of exogenous stimulators of adenosine 3',5'-cyclic monophosphate formation, cytosolic Ca2+ transients, or cell swelling.


Intracavitary ultrasound impairs left ventricular performance: presumed role of endocardial endothelium.

Irradiation of isolated cardiac muscle by high-power, high-frequency, continuous wave ultrasound selectively damages endocardial endothelium (EE). We evaluated this ultrasound effect in vivo on the performance of the intact ejecting canine left ventricle (LV). A cylindrical ultrasound probe (0.9 MHz, 25 W), mounted on a catheter, was inserted in the LV cavity through an apical stab wound and was activated for 60, 120, and 240 s, followed each time by a recovery period of 10-15 min. Ultrasound transiently and repeatedly abbreviated the time interval from end diastole to peak (-)dP/dt (from 241 +/- 30 to 229 +/- 32 ms after 240 s; P < 0.001), accelerated LV pressure fall, did not alter peak (+)-dP/dt or peak systolic pressure, increased diastolic and systolic segment lengths, and decreased fractional shortening. Microscopic analysis revealed dispersed granulocytes attached to the EE. EE cells were visibly damaged only in a limited area surrounding the probe. Accordingly, high-power, high-frequency, continuous wave ultrasound reversibly modulated LV performance, presumably by transient alteration of EE function.


Advance shift of feeding circadian rhythm induced by obesity progression in Zucker rats.

To determine the relation between the circadian rhythm of ingestive behavior and the progression of obesity in Zucker rats, ingestion and ambulation were analyzed at four different developmental stages. The obese rats were disrupted gradually in nocturnal patterns of feeding, drinking, and ambulation with the progression of obesity, although the lean littermates maintained the patterns during whole test periods. Analysis of autocorrelogram revealed that circadian rhythms of those behaviors remained throughout the whole test periods. Least-squares spectrum ascertained the following. 1) The obese made advance shift of acrophases in feeding and drinking circadian cycles, but not in ambulation. 2) Amplitudes in those behavioral measures decreased with the progression of obesity. 3) Mesor in the obese feeding was not affected, although that in the lean feeding decreased. The findings indicate that disruption of the light-dark cycle in ingestion of the obese was not due to disappearance of circadian rhythm but to transformation by both decreased amplitude and advance shift of the circadian cycle.


Role of sympathetic innervation in brown adipocyte proliferation.

The role of sympathetic nerves in the control of brown adipose tissue (BAT) growth was studied by quantitative photonic autoradiography using [3H]-thymidine to follow mitotic activity. The effects of cold exposure (4 days at 5 degrees C) and chronic norepinephrine treatment (0.375 mumol/h for 4 days at 25 degrees C) were compared in intact and denervated interscapular BAT pads of adult rats. The denervated pads were paler than the contralateral innervated sides and contained numerous adipocytes filled with large lipid droplets. In the innervated BAT pad, cold exposure markedly enhanced the labeling frequency in brown adipocyte precursor cells (interstitial cells and preadipocytes) and in endothelial cells forming the numerous blood capillaries (P < 0.01). However, in the denervated BAT pads, the effects of cold exposure on cell proliferation were markedly inhibited. Remarkably, norepinephrine infusion at 25 degrees C mimicked the effects of cold exposure on the coordinated proliferation of the different cellular types, both in the innervated and denervated pads. These results demonstrate that intact sympathetic nerves are required for the stimulation of mitotic activity in BAT by cold exposure but not by norepinephrine infusion. It appears therefore that norepinephrine release from sympathetic nerves represents the initial stimulus in a chain of metabolic events leading to BAT hyperplasia. However, sympathetic or sensory nerves may still contain factors modulating cell proliferation and differentiation in BAT.


Intrarenal pressures during direct inhibition of sodium transport.

Renal interstitial hydrostatic pressure (RIHP) has been implicated in the regulation of sodium excretion. Studies using vasodilators and other maneuvers to increase RIHP have found a significant correlation between RIHP and sodium excretion. Since correlative studies do not prove a cause-and-effect relationship, it is not known whether the rise in sodium excretion in these studies is the result of increases in RIHP or if RIHP is elevated as a result of decreases in sodium and water reabsorption and increases in intratubular pressure. Therefore, the purpose of the present study was to determine whether elevation of intratubular hydrostatic pressures in response to direct inhibition of tubule transport with loop diuretics results in increases in RIHP in dogs and rats. Intrarenal hydrostatic pressures, renal hemodynamics, and sodium and water excretion were examined in dogs during intravenous administration of furosemide (3 mg/kg bolus followed by 0.03 mg.kg-1 x min-1) or bumetanide (60 micrograms/kg bolus followed by 1 microgram.kg-1 x min-1). Furosemide administration increased urinary flow rate (V; 0.10 +/- 0.02 to 4.6 +/- 0.97 ml/min), urinary sodium excretion (UNaV; 16 +/- 5 to 549 +/- 123 mu eq/min), and proximal tubule hydrostatic pressure (PT; 21 +/- 1 to 28 +/- 1 mmHg) but had no effect on RIHP (7.2 +/- 0.6 to 7.4 +/- 0.7 mmHg) or peritubular capillary hydrostatic pressure (14 +/- 1 to 14 +/- 1 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)


Vasopressin-induced suppression of renal sympathetic outflow depends on the number of baroafferent inputs in rabbits.

We tested the hypothesis that the inhibitory action of arginine vasopressin (AVP) on renal sympathetic nerve activity (RSNA) is related to the number of baroreceptor stations. The role of baroreceptor afferents was determined by comparing the effects of AVP on the baroreflex function curves [mean arterial pressure (MAP) vs. %RSNA] obtained in intact conscious rabbits with those obtained in rabbits with one carotid sinus and one aortic nerve intact (1CSN + 1AoN) and in rabbits with only a single carotid sinus nerve intact (1CSN). Baroreflex curves were obtained by relating %RSNA to MAP during ramp increases and decreases in MAP. MAP was increased with phenylephrine and decreased with caval occlusion. In the intact state (n = 7), AVP infusions (0.4, 1.5, and 3.0 mU.kg-1 x min-1) produced dose-dependent reduction in the maximum %RSNA (97 +/- 1 to 85 +/- 6, 68 +/- 6, and 57 +/- 5%, respectively) at minimum MAP and the gain of the baroreflex curve (5.7 +/- 0.2 to 3.9 +/- 0.2, 3.2 +/- 0.3, and 2.2 +/- 0.2 mmHg, respectively) and shifted the midrange of the curves (72 +/- 3 to 68 +/- 4, 68 +/- 2, and 63 +/- 3 mmHg, respectively). However, in the 1CSN + 1AoN state (n = 6), the medium dose of AVP (1.5 mU.kg-1 x min-1) did not significantly alter the maximum %RSNA, the gain of the curve, or the midrange of the curve. The highest dose of AVP (3.0 mU.kg-1 x min-1) still reduced the maximum %RSNA (98 +/- 3 to 75 +/- 3) and the gain of the curve (4.1 +/- 0.4 to 2.7 +/- 0.2).(ABSTRACT TRUNCATED AT 250 WORDS)


Medullary pathway of the Bezold-Jarisch reflex in the rat.

The central pathway mediating the Bezold-Jarisch reflex elicited by jugular vein injection of serotonin (5-HT) and phenyl biguanide (PBG) was studied in halothane-anesthetized, paralyzed rats. 5-HT and PBG produced hypotension and inhibition of lumbar sympathetic discharge often preceded by sympathoexcitation. The Bezold-Jarish reflex was blocked by bilateral kynurenic acid (KYN; glutamate antagonist, 1.25 nmol/side) microinjection into the solitary tract nucleus. Bilateral KYN injection into the caudal ventrolateral medulla (5 nmol/side) also blocked the reflex. Bilateral injection of bicuculline methiodide (BIC; 100 pmol/side) into the rostral ventrolateral medulla (RVL) reduced the depressor and sympathoinhibitory components of the reflex and enhanced an excitatory component. Blockade or attenuation of the Bezold-Jarisch reflex was always associated with a concomitant blockade or attenuation of the arterial baroreflex. RVL barosensitive neurons (n = 61) were inhibited (> 60% reduction in firing) by PBG and 5-HT. Iontophoretic application of BIC (n = 11 cells), but not strychnine (glycine antagonist), blocked inhibition of RVL neurons by 5-HT and PBG. The sympathoinhibitory component of the Bezold-Jarisch reflex may use a central pathway similar to that of the arterial baroreflex.


Effects of fasting and hibernation on ion secretion in ground squirrel intestine.

Ground squirrels were used to study the effects of fasting and hibernation on small intestinal secretory function. Muscle-stripped sheets of jejunum set up in flux chambers were challenged with a variety of secretory agonists, and changes in short-circuit current (Isc) were recorded. Mucosal wet weights per centimeter and crypt dimensions were not affected by a 3-day fast in active squirrels, but villus height and area were significantly reduced in hibernators that had not eaten for over 6 wk. Tissue conductance was significantly greater in fasted and hibernating squirrels compared with fed animals. Maximal changes in Isc evoked by electrical stimulation of submucosal neurons, normalized to serosal surface area, were greater in fasted compared with fed or hibernating squirrels. When responses were normalized to crypt area, neurally evoked changes in Isc were greatest in the hibernators. Carbachol and serotonin evoked dose-dependent changes in Isc that were greater in fasted compared with fed squirrels at all concentrations. Histamine (100 microM) and theophylline (1 mM) also produced greater increases in Isc in fasted than in fed squirrels. The results suggest that a 3-day fast, or the extended fast of hibernation, results in enhanced secretory capacity in the ground squirrel jejunum.


Intestinal secretion after jejunal bypass in the ground squirrel.

The preceding paper [H. V. Carey, Am. J. Physiol. 263 (Regulatory Integrative Comp. Physiol. 32): R1202-R1208, 1992] demonstrated that a 3-day fast or the extended fast of hibernation enhanced the chloride secretory responses to a variety of agonists in the ground squirrel jejunum. Here we examined the effect of jejunal bypass on intestinal secretory capacity in squirrels that either remained active and continued to feed (ACT), or were induced to hibernate (HIB). Mucosal wet weights were reduced in jejunal segments that had little or no exposure to the luminal stream (all segments from HIB and bypassed segments from ACT) compared with segments in contact with luminal contents (sham and in continuity segments of ACT). Tissue conductances were greater in those segments not exposed to luminal contents. Short-circuit current (Isc) responses to electrical stimulation of submucosal neurons, or to serosal carbachol, were greater in segments not exposed to luminal contents when responses were normalized to serosal surface area. Normalization of secretory responses to crypt area produced a similar pattern. Isc responses to mucosal alanine, which reflect electrogenic Na+ absorption, were greatest in segments with little or no exposure to luminal contents. Tissue wet weights, conductances and secretory responses of bypassed segments of HIB and ACT squirrels were always similar. These results suggest that luminal contents directly influence jejunal secretory capacity.


Cholecystokinin reduces body temperature in vehicle- but not capsaicin-pretreated rats.

Systemic administration of cholecystokinin C-terminal octapeptide (CCK-8) decreases body temperature. However, it remains unclear whether reduction of body temperature is concomitant with suppression of food intake at CCK-8 doses that approach physiological levels. We examined rectal temperature after intraperitoneal CCK-8, 4 micrograms/kg, both in the presence and absence of a preferred food. We found that rectal temperature was significantly reduced by CCK-8 in both conditions and that the reduction of temperature coincided with the time of maximal suppression of food intake by CCK-8. In rats pretreated systemically with 25 or 175 mg/kg of the sensory neurotoxin capsaicin, both suppression of food intake and reduction of body temperature were significantly attenuated or abolished. The 25 mg/kg capsaicin treatment did not alter corneal chemosensitivity or the ability of rats to maintain normothermia at elevated ambient temperature, suggesting that capsaicin damage to neural substrates mediating CCK-8-induced reduction of body temperature 1) did not generalize to cephalic or peripheral warm-sensitive structures, and 2) was limited to fine sensory fibers accessible to intraperitoneal capsaicin application.


Effects of ventromedial hypothalamic stimulation on glucose transport system in rat tissues.

Electrical stimulation of the ventromedial hypothalamus (VMH) increased the rate constant of glucose uptake in rat heart and brown adipose tissue (BAT), as measured in vivo by the 2-deoxy-D-[3H]glucose method. The increase in glucose uptake in BAT was abolished by local sympathetic denervation. To analyze the mechanism of this hypothalamic modulation, the effects of VMH stimulation and insulin treatment on the number and dissociation constant (Kd) of glucose transporters in the plasma and microsomal membranes were examined by means of [3H]cytochalasin B binding. VMH stimulation did not alter either the number or Kd value of glucose transporters in plasma and microsomal membranes prepared from heart and BAT, whereas insulin treatment increased the number of glucose transporters in the plasma membranes and decreased those in the microsomal membranes. D-Glucose transport activity was also measured with the same plasma membrane vesicles. An apparent functional activity of transporters was detected to be increased in the heart and BAT plasma membranes after VMH stimulation but not after insulin treatment. These results suggest that VMH stimulation enhances glucose utilization in heart and BAT via sympathetic innervation and that the mechanism by which VMH stimulation increases tissue glucose uptake is different from that of insulin, possibly causing an activation of glucose transporters present in the plasma membrane.


A critical role for central vasopressin in regulation of fever during bacterial infection.

Previous investigations on the antipyretic properties of arginine vasopressin have used bacterial endotoxins or pyrogens to induce fever. Because these experimental models of fever fail to mimic all aspects of the responses to infection, we felt it was important to examine the role of endogenously released vasopressin as a neuromodulator in febrile thermoregulation during infection. Therefore the present study examines the effects of chronic infusion of a V1-receptor antagonist or saline (via osmotic minipumps into the ventral septal area of the brain) on a fever induced by injection of live bacteria. Telemetry was used for continuous measurement of body temperature in the awake unhandled rat. Animals infused with the V1-antagonist exhibited fevers that were greater in duration compared with those of saline-infused animals. These results support the hypothesis that vasopressin functions as an antipyretic agent or fever-reducing agent in brain. Importantly, they suggest that endogenously released vasopressin may play a role as a neuromodulator in natural fever.


Effects of estrogen on whole animal and tissue glucose use in female and male rainbow trout.

Reports of changes in carbohydrate metabolism during vitellogenesis in fish prompted an investigation of the effects of estrogen on glucose utilization in rainbow trout. Estrogen pellets were implanted in both female and male fish, and a third group of male fish was given a sham operation. After cannulation of the dorsal aorta, D-[1-3H]glucose and 2-deoxy-D-[U-14C]glucose were injected into the fish to observe whole animal and tissue glucose use. We found that estrogen does not affect glucose turnover rate or transit time but causes a decrease in plasma glucose concentration and size of the glucose mixing pool. Adipose tissue in female fish utilized glucose at a higher rate than sham fish. Ovarian tissue used more glucose per kilogram of body weight than the testes of the male fish. Regardless of treatment, brain had the highest rate of glucose consumption per gram of tissue, followed by gonads and red blood cells. Muscle and adipose tissue utilized only small amounts (< 1 nmol.g tissue-1.min-1) of glucose. We conclude that an increase in the rate of whole body glucose use is not responsible for the fall in plasma glucose caused by estrogen and seen during vitellogenesis.


Adipose tissue lipolysis in vitro: a predictor of diet-induced obesity in female rats.

Wide ranges in weight and fat gain in response to high-fat diets have been reported in rats. This study measured epinephrine-stimulated lipolysis in adipose tissue of normal weight, 3-mo-old, female Sprague-Dawley rats as a metabolic predictor of "efficient gain" before feeding them a high-fat (84% kcal) diet for 11 wk. Subcutaneous (inguinal) adipose tissue (1-1.5 g) was excised, and the glycerol release was measured after incubation with 0, 10(-7), 10(-5), and 10(-3) M epinephrine. Differences in gain efficiency explained much of the variation in lipid (r = 0.78) and weight (r = 0.83) gain. Low glycerol release by 10(-5) and 10(-3) M epinephrine was significantly correlated to high final fat accumulation. Low and high quartiles based on glycerol release were not different in numbers of adipocytes or food intake but were significantly different in gain efficiency (P = 0.011), final weight (P = 0.036), carcass lipid (P = 0.033), and carcass lean mass (P = 0.017). In conclusion, female Sprague-Dawley rats are preferentially predisposed to efficiency of adipose accumulation on a high-fat diet. This tendency is negatively correlated in the preobese state to the lipolytic response to epinephrine of subcutaneous adipose tissue in vitro.


Luminal pH in the amphibian distal tubule: effects of carbonic anhydrase and carbonic anhydrase inhibitors.

To better delineate acid-base transport properties in the distal tubule (DT) of Necturus in vivo, we 1) studied the effects of peritubular (pt) isohydric increase of PCO2 and [HCO3-]pt on luminal pH (pHlu), and 2) measured the steady-state pHlu under various experimental conditions. The experiments were carried out on initial (DTi) or distal (DTd) loops of the DT in control state and then during intravenous infusion of carbonic anhydrase (CA) or CA inhibitors (CAI). In control state, isohydric increase of PCO2 and [HCO3-]pt results in transient acidification of the DTi lumen, whereas in DTd lumen the same maneuver yields sustained (plateau) acidification. Under systemic infusion of CAI, isohydric increase of PCO2 and [HCO3-]pt lowers pHlu (sustained fall of pHlu) in DTi and DTd, whereas under CA infusion both segments exhibit only transient acidification. During intravenous infusion with benzolamide DTi steady-state pHlu falls, suggesting that this maneuver inhibits a functional luminal CA, in contrast to the DTd, whose pHlu remains unaltered. Intravenous infusion of CA significantly increases steady-state DTd pHlu; by contrast, steady-state pHlu in DTi does not change. These data are consistent with the presence of functional luminal CA in the DTi, whereas the DTd segment lacks the luminal enzyme.


Normobaric hypoxia stimulates endothelin-1 gene expression in the rat.

The current study tested the hypothesis that exposure to hypoxia enhances endothelin-1 (ET-1) gene expression and elevates circulating ET-1 levels in the rat. Rats were exposed to normobaric hypoxia (10% O2) or room air for 24 or 48 h. ET-1 in arterial blood was measured by radioimmunoassay. ET-1 gene transcript levels were measured by the slot blot technique on total RNA isolated from lung, right and left atria, right and left ventricles, kidney, spleen, liver, brain, main trunk of pulmonary artery, and thoracic aorta. Blots were probed with a 0.5 kb rat prepro ET-1 cDNA that does not cross-hybridize with mRNA for ET-2 or ET-3. Plasma ET-1 levels were increased significantly at 24 (10.03 +/- 2.33 pg/ml) and 48 h (14.02 +/- 3.44 pg/ml) of hypoxia compared with air controls (4.14 +/- 0.66 pg/ml). ET-1 mRNA levels were increased significantly (2-fold) in lung and right atrium after 48 h of hypoxia; no change was seen in organs perfused by the systemic vascular bed. These findings suggest that the hypoxia-induced increase in circulating ET-1 levels is mainly of pulmonary origin. A paracrine effect of ET-1 produced by lung endothelial cells could account for hypoxic pulmonary hypertension.


Do renal nerves chronically influence renal function and arterial pressure in spinal rats?

Previous studies have demonstrated that renal nerve activity has acute effects on renal function in rats with cervical spinal cord transection (CST). The present study tested the hypothesis that renal nerves chronically influence renal and cardiovascular function in CST rats. Three groups of conscious Sprague-Dawley rats were studied: renal denervated plus CST (RDNX + CST), sham RDNX plus CST (sham + CST), and sham RDNX plus sham CST (intact). CST or sham CST surgeries were performed 8 days after RDNX or sham RDNX. Sodium and water intakes were fixed by intravenous infusion. Mean arterial pressure (MAP) and plasma renin activity (PRA) were measured before and for 9 days after CST/sham CST. In addition, urine flow, urinary sodium excretion, and urine pH were measured in the two groups of CST rats. One day after CST, MAP decreased approximately 25 mmHg in both RDNX + CST and sham + CST groups. PRA had fallen approximately 50% 1 day after CST and was not different between CST groups. PRA remained depressed throughout the study. There were no differences between sham + CST and RDNX + CST rats in any of the renal or cardiovascular variables measured after CST. In summary, we found no evidence for a chronic effect of renal nerves on renal function or arterial pressure in CST rats.


Metabolic and respiratory effects of infused sodium acetate in healthy human subjects.

The metabolic and respiratory effects of intravenous 0.5 M sodium acetate (at a rate of 2.5 mmol/min during 120 min) were studied in nine normal human subjects. O2 consumption (VO2) and CO2 production (VCO2) were measured continuously by open-circuit indirect calorimetry. VO2 increased from 251 +/- 9 to 281 +/- 9 ml/min (P < 0.001), energy expenditure increased from 4.95 +/- 0.17 kJ/min baseline to 5.58 +/- 0.16 kJ/min (P < 0.001), and VCO2 decreased nonsignificantly (211 +/- 7 ml/min vs. 202 +/- 7 ml/min, NS). The extrapulmonary CO2 loss (i.e., bicarbonate generation and excretion) was estimated at 48 +/- 5 ml/min. This observation is consistent with 1 mol of bicarbonate generated from 1 mol of acetate metabolized. Alveolar ventilation decreased from 3.5 +/- 0.2 l/min basal to 3.1 +/- 0.2 l/min (P < 0.001). The minute ventilation (VE) to VO2 ratio decreased from 22.9 +/- 1.3 to 17.6 +/- 0.9 l/l (P < 0.005), arterial PO2 decreased from 93.2 +/- 1.9 to 78.7 +/- 1.6 mmHg (P < 0.0001), arterial PCO2 increased from 39.2 +/- 0.7 to 42.1 +/- 1.1 mmHg (P < 0.0001), pH from 7.40 +/- 0.005 to 7.50 +/- 0.007 (P < 0.005), and arterial bicarbonate concentration from 24.2 +/- 0.7 to 32.9 +/- 1.1 (P < 0.0001). These observations indicate that sodium acetate infusion results in substantial extrapulmonary CO2 loss, which leads to a relative decrease of total and alveolar ventilation.


AV3V lesion impairs responses induced by cholinergic activation of SFO in rats.

This study was performed to investigate the effect of lesion of the anteroventral third ventricle (AV3V) region on the pressor, bradycardic, dipsogenic, natriuretic, kaliuretic, and antidiuretic responses induced by cholinergic activation of the subfornical organ (SFO) in rats. Male Holtzman rats with sham or electrolytic AV3V lesion were implanted with a stainless steel cannula directly into the SFO. Microinjection of the cholinergic agonist carbachol (2 nmol) into the SFO of sham rats induced natriuresis (563 +/- 70 mu eq/120 min), kaliuresis (205 +/- 13 mu eq/120 min), antidiuresis (10.4 +/- 0.5 ml/120 min), water intake (9.3 +/- 1.4 ml/h), bradycardia (-42 +/- 11 beats/min), and increased mean arterial pressure (53 +/- 3 mmHg). In AV3V-lesioned rats (1-5 and 14-18 days), there was a reduction of natriuresis (23 +/- 11 and 105 +/- 26 mu eq/120 min, respectively), kaliuresis (92 +/- 16 and 100 +/- 17 mu eq/120 min), water intake (2.5 +/- 0.9 and 1.8 +/- 1.0 ml/h), and arterial pressure increase (17 +/- 2 and 16 +/- 2 mmHg) induced by carbachol into the SFO. Increased antidiuresis (6.0 +/- 1.0 and 5.2 +/- 0.7 ml/120 min, respectively) and tachycardia (39 +/- 4 and 15 +/- 12 beats/min) instead of bradycardia were also observed in both groups of AV3V-lesioned rats. These results show that cholinergic activation of the rat SFO produces marked natriuresis and kaliuresis in addition to the well-known pressor and dipsogenic responses. They also show that the AV3V region plays an important role in the cardiovascular, fluid, and electrolytic changes induced by cholinergic activation of the SFO in rats.


Detrusor hyperplasia and expression of "immediate early" genes with onset of abnormal urodynamic parameters.

To determine the stimulus for growth of the detrusor with a pathophysiological obstruction to the urinary stream, we studied urodynamic parameters, detrusor weight, detrusor DNA content, and the expression of early growth-related protooncogenes in a model of gradual onset bladder outflow obstruction and reversal of obstruction. Silver jeweler's jump rings were placed loosely round the urethra of immature guinea pigs, allowing an obstruction to develop gradually with animal growth. At 1, 2, 4, and 8 wk after surgery, animals were killed after urodynamic studies under urethan anesthesia. Bladders were removed, and mucosa-free detrusor was weighed and frozen for assay of DNA content and expression of c-fos and c-myc protooncogenes. Results were compared with sham-operated age-matched control animals. One week after surgery there was no change in the urodynamic parameters, detrusor weight, or DNA content. At 2, 4, and 8 wk after placement of the silver rings, animals developed obstructive voiding patterns, an increase in detrusor weight, and total DNA content. The onset of obstructive voiding patterns correlated with transient increased levels of c-fos and c-myc mRNA by Northern blot analysis. Autoradiography of in vivo [methyl-3H]thymidine-labeled detrusor muscle from obstructed animals showed myocyte DNA synthesis and mitosis, implying myocyte hyperplasia. After removal of the silver ring, the obstructive voiding patterns resolved and detrusor weight and DNA content returned to levels of the control animals. These results suggest that in the guinea pig bladder subjected to a gradual onset outflow obstruction, detrusor growth is initiated by the development of obstructive voiding patterns.(ABSTRACT TRUNCATED AT 250 WORDS)


Adrenergic vasomotor responses in nasal mucosa of hooded seals.

In seals respiratory heat and water losses are restricted through nasal heat exchange. The heat exchange efficiency is apparently controlled through adjustments in the nasal mucosal blood flow rate and/or pattern. In this study the adrenergic mechanisms involved in regulation of mucosal blood flow were investigated. The nasal mucosal vasculature of 14 newly killed hooded seal (Cystophora cristata) pups was perfused by a constant-flow peristaltic pump with 37 degrees C oxygenated modified Krebs solution via the sphenopalatine arteries. The effects of single-dose injections of various drugs on resistance to flow were monitored with a pressure transducer. Epinephrine, norepinephrine, alpha 1-adrenoceptor agonist phenylephrine, alpha 2-agonist clonidine, beta 1-agonist dobutamine, and beta 2-agonist terbutaline caused transient pressure increases that were blocked by alpha-adrenoceptor antagonists. Papaverine and vasoactive intestinal polypeptide induced vasodilatation, showing that some basal vascular tone was present. Nevertheless, the beta 1- and beta 2-agonist isoproterenol had no effect on resistance, and none of the beta-agonists attenuated the pressor responses to alpha-agonists. In conclusion, adrenergic control of nasal mucosal blood flow in seals is essentially exerted through alpha-adrenoceptor-mediated arteriolar constriction, whereas beta-adrenoceptor-mediated dilatation seems to be of little importance. It is suggested that such sympathoadrenergic vascular mechanisms contribute to control nasal heat exchange efficiency in seals.


Cerebral anoxia tolerance in turtles: regulation of intracellular calcium and pH.

To investigate mechanisms of cerebral anoxia tolerance, cerebrocortical intracellular calcium ([Ca2+]i) and pH (pHi) regulation were compared in turtles (Trachemys scripta) and laboratory rats. [Ca2+]i and pHi in living 200 to 300-microns-thick cortical brain slices were measured with the fluorescent indicators fura-2/acetoxymethyl ester (AM) and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein during exposure to anoxia. Within 5 min, [Ca2+]i increased to > 1,000 nM in rat brain slices exposed to anoxia but [Ca2+]i was normal even after 5 h of anoxia in turtles. ATP levels remained normal in anoxic turtle brain but fell rapidly in rats. During anoxia, pHi fell by 0.25 +/- 0.08 pH units in rats but only 0.10 +/- 0.04 in turtles (P < 0.05). Inhibition of glycolysis in anoxic turtle brain with iodoacetate resulted in large increases in [Ca2+]i but prior exposure of slices to anoxia resulted in greatly attenuated calcium entry. The reduction in calcium flux was greater with increasing exposure to anoxia, suggesting progressive arrest of calcium channel activity. Tolerance of cerebral anoxia in turtles may be related to anaerobic ATP production, arrest of calcium channels, and attenuation of changes in pHi.


ANP-mediated volume depletion attenuates renal responses in humans.

Brief low-dose infusions of atrial natriuretic peptide (ANP) that emulate physiological plasma concentrations in humans have little if any effect on renal excretory function. This study explored the possibility that ANP-mediated reductions in cardiac filling pressures (through ANP's rapid effect on capillary dynamics) could attenuate its purported renal effects. Protocol A consisted of 16 healthy subjects (ages 19-27 yr old) who underwent three consecutive 45-min experimental sequences: 1) placebo, 2) ANP (10 ng.kg-1 x min-1), and 3) ANP alone (n = 8) or ANP with simultaneous lower body positive pressure (LBPP, n = 8). Electrocardiogram and direct measures of arterial and central venous pressures were continuously monitored. Blood was sampled at the end of each 45-min sequence before subjects stood to void. Compared with control (placebo), ANP produced a hemoconcentration and increased plasma norepinephrine, but did not change heart rate, blood pressure, plasma levels of renin, aldosterone, or vasopressin, or renal excretion of volume or sodium. In subjects receiving LBPP to maintain central venous pressure during the last 45 min of ANP infusion, norepinephrine did not increase and urine volume and sodium excretion increased (P < 0.05). In a second study (protocol B), five healthy subjects received a placebo infusion for 45 min followed by two consecutive 45-min infusions of ANP (10 ng.kg-1 x min-1). Central venous pressure was maintained (LBPP) at placebo baseline throughout the two ANP infusion periods. Urine volume and sodium excretion rates increased progressively and significantly during both ANP infusion periods (P < 0.05) without significant changes in creatinine clearance, blood pressure, or heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)


Metabolic responses to forced dives in Pekin duck measured by indirect calorimetry and 31P-MRS.

We tested the hypothesis that forced-dived ducks experience a reduction in metabolic rate during prolonged submergence. Unidirectionally ventilated conscious ducks were subjected to forced dives by temporarily stopping the airflow in the ventilation system and simultaneously filling a face mask with cold water. A typical cardiovascular response to submergence was observed: bradycardia and maintained arterial blood pressure. Phosphorylated metabolite concentrations in the pectoral muscle were measured noninvasively by phosphorus magnetic resonance spectroscopy (31P-MRS). ATP content was constant, and phosphocreatine was depleted via the creatine kinase reaction at a rate similar to the resting rate of ATP turnover, which was estimated to be 0.9 mumol.min-1 x g-1 in resting perfused pectoral muscle of pentobarbital-anesthetized ducks. Oxygen from myoglobin supplied at most 12% of the ATP required by the resting muscle during dives. Whole animal postdive excess oxygen consumption and blood lactic acid accumulation suggested that the shortfall in aerobic metabolism during forced dives was compensated by an increase in anaerobic metabolism.


In vivo longitudinal variations in protein synthesis in developing ovine intestines.

Changes in fractional rates of protein synthesis (Ks) were investigated at different small and large intestinal sites in 1-, 5-, and 8-wk-old milk-fed and 8-wk-old weaned lambs, a species with early intestinal maturation similar to most domestic animals and humans, with the use of a flooding dose of L-[3H]valine. Between 1 and 8 wk of age, Ks did not change significantly in the duodenum, the cecum, or the colon of milk-fed lambs, but was depressed by 30% in the jejunum and by 39% in the ileum. This was because of reduced ribosomal capacity, i.e., total RNA-to-protein ratio (Cs) in the jejunum, and also alterations in both Cs and protein synthetic efficiency, i.e., rate of synthesis relative to RNA (KRNA) in the ileum. Ks values throughout the small intestine were significantly higher (45-55%) in weaned lambs than in 8-wk-old milk-fed animals. This enhancement of protein synthesis was mainly related to an increase in KRNA (27-40%). Ks decreased by 43% from the duodenum to the ileum in both milk-fed and weaned 8-wk-old animals, but not in 1- and 5-wk-old milk-fed lambs, because of a marked reduction in KRNA. It was concluded that changes in nutrients at weaning, weaning itself, or both, enhanced protein synthesis without any specific effect on small intestinal site. By contrast, intrinsic developmental factors were responsible only for the regional differences in small intestinal Ks that occurred at 8 wk of age. Longitudinal variations in protein synthesis may contribute to the establishment of the well-recognized jejunoileal gradients of brush-border enzymes and villus height that characterize the mature mammalian small intestine.


Angiotensin II receptor activation depolarizes rat supraoptic neurons in vitro.

Functional studies indicate that hypothalamic magnocellular neurosecretory neurons are a target for angiotensin. The present investigation used intracellular recordings to characterize the nature and type of angiotensin II receptors on rat supraoptic nucleus neurons maintained in superfused hypothalamic explants. Of 68 cells transiently exposed to either Val5- or Ile5-angiotensin II (maximum peak concentration 1-25 microM), 34 responded with a gradual membrane depolarization (1-15 mV) that peaked in 2.2 +/- 0.4 (SD) min and was accompanied by a 17.6 +/- 4.8% reduction of input resistance. Responses persisted (and were actually enhanced) in media containing tetrodotoxin (0.5-1.0 microM) and/or nominally zero calcium, indicating a direct postsynaptic action. In 19 responsive cells, the mean reversal potential for the angiotensin-induced response was -26.4 +/- 2 mV. Bath application of the nonpeptide type-1 angiotensin receptor antagonist DuP753 (5-20 microM) reversibly blocked the angiotensin-induced depolarization in all of 11 cells tested. By contrast, equimolar applications of the type-2 antagonist PD123177 were ineffective in all seven angiotensin-responsive cells tested. These observations provide novel evidence for the existence of functional type-1 receptors on rat supraoptic nucleus neurons. The reversal potential for the angiotensin-induced response suggests mediation through a nonselective cationic conductance.


Modulation of sleep by cortisone in normal and bacterially infected rabbits.

Infectious disease is known to alter both sleep patterns and hydrocortisone (cortisol) concentrations in rabbits. Moreover, the sleep-altering effects of microbial infections are likely to be mediated via endogenous immune modulators whose actions are attenuated by glucocorticoids. To evaluate the relationships between sleep and glucocorticoids during infectious disease, the effects of cortisone administration (20 mg/kg, im) on sleep were examined before and after inoculation of rabbits with Staphylococcus aureus or Escherichia coli. When administered alone, cortisone did not alter the amount of time spent in slow-wave sleep (SWS) but did reduce electroencephalographic (EEG) slow-wave amplitudes during SWS, the number of bouts of SWS and the amount of time spent in rapid-eye-movement sleep. The duration of individual bouts of SWS was increased after cortisone treatment. Bacterially infected rabbits developed biphasic changes in sleep patterns that were characterized by an initial increase and a subsequent decrease both in SWS time and in EEG slow-wave amplitudes during sleep. Cortisone treatment attenuated these effects in S. aureus-inoculated rabbits. In contrast, cortisone treatment did not alter the initial phase of enhanced sleep in E. coli-inoculated rabbits but did attenuate the subsequent sleep suppression. These data indicate that glucocorticoid administration is associated with an attenuated sleep response in bacterially inoculated rabbits.


Abdominal vagal mediation of the satiety effects of exogenous and endogenous cholecystokinin in rats.

The hypothesis that peripherally administered cholecystokinin C-terminal octapeptide (CCK-8) and endogenous CCK act by the same abdominal vagal mechanism to produce satiety was tested by injecting rats with CCK-8 or the type A CCK receptor antagonist MK-329 after they had received bilateral subdiaphragmatic vagotomies. CCK-8 (8 nmol/kg ip) inhibited 1-h food intake by 60%; vagotomy and MK-329 (0.5 mg/kg sc) each completely blocked this effect. In contrast, vagotomy did not alter the stimulatory effect of MK-329 (0.5 mg/kg sc) on feeding; 3-h cumulative intake in control and vagotomized animals was increased by 25 and 34%, respectively. These results suggest that satiety is mediated in part by an endogenous CCK action that is independent of abdominal vagal innervation.


Individual differences in afterimage persistence: relationships to hypnotic susceptibility and visuospatial skills.

To investigate the moderating role of individual differences in hypnotic susceptibility and visuospatial skills on afterimage persistence, we presented a codable (cross) flash of light to 40 men and 46 women who had been dark adapted for 20 min. In an unrelated classroom setting, subjects had previously been given two standardized scales of hypnotic susceptibility (Harvard Group Scale of Hypnotic Susceptibility, Shor & Orne, 1962; Group Stanford Hypnotic Susceptibility Scale, Form C, Crawford & Allen, 1982) and the Mental Rotations Test (Vandenberg & Kuse, 1978). The first afterimage interval and the afterimage duration correlated significantly with hypnotic responsiveness, supporting Wallace (1979), but did not show the anticipated relationships with mental rotation visuospatial skills. Individuals in the high hypnotizable group had (a) significantly longer afterimage intervals between its first appearance and first disappearance than did those in medium or low groups, as well as (b) significantly longer afterimages between the first appearance and the final disappearance than did those in low groups, but those in medium groups did not differ significantly from the other groups. Discriminant analysis using the afterimage persistence measures classified correctly 65.2% of high hypnotizables, 37.5% of medium hypnotizables, and 54.8% of low hypnotizables. Hypothesized cognitive skills that assist in the maintenance of afterimages and underlie hypnotic susceptibility include abilities to maintain focused attention and resist distractions over time and to maintain vivid visual images.


Priming and aging: evidence of preserved memory function in an anagram solution task.

Priming effects in a test of anagram solution were compared with recognition memory in young and older adults. Age and a levels-of-processing study manipulation had little influence on priming in the anagram solution task, whereas significant effects of both of these variables were obtained in a recognition test. These findings extend those of previous studies which have shown little evidence of age differences in implicit memory tasks compared with those of explicit memory. Furthermore, they provide evidence for classifying anagram solution as an implicit memory test.


Very long-term memory for odors: retention of odor-name associations.

The ability to remember odor-name associations for recent odors (those associated with everyday products experienced within the past 2 years) and distant odors (those associated with children's toys not encountered for 3 years or more) was examined in two experiments. In recognition tasks, subjects attempted to match odor names to odors, or odors to odor names. In a recall task, subjects tried to identify odors by name. The results showed that although odor retention was better for recent than distant odors, significant retention remains for odors not experienced since childhood. These results are consistent with other studies that found very slow and gradual loss of odor information in memory. They extend that research by showing that odor information is still available over a much longer period of time.


Utilization of base-rate information during feeling-of-knowing judgments.

We examined whether subjects use base-rate information about item difficulty when making feeling-of-knowing judgments for items they failed to recall. First, the subjects attempted to recall the answers to general-information questions. Then, for those items they recalled incorrectly, half of the subjects received information about the normative probability of recall of each item while judging their feeling of knowing. The other subjects made their feeling-of-knowing judgments without receiving any base-rate information. Finally, all subjects had a forced-choice recognition test on those items to validate the accuracy of their feeling-of-knowing judgments. Relative to the no-base-rate information group, the base-rate group had lower feelings of knowing for normatively difficult items and higher feelings of knowing for normatively easier items. Subjects who had received base-rate information during the judgment state had greater feeling-of-knowing accuracy than subjects who did not receive base-rate information. However, even the predictions from subjects who received base-rate information were not significantly more accurate for predicting subsequent recognition than were the predictions derived from normative information alone.


[Anti-vascular antibodies in women with physiological pregnancy and pregnancy complicated by gestosis].

Immunologic manifestations of injury to the vascular wall were studied in 191 pregnant women. Blood serum ++anti-vascular antibodies were analyzed by passive hemagglutination, complement fixation, and precipitation tests. ++Anti-vascular antibodies were found in all the women with a normal pregnancy course. Normal pregnancy was characterized by clear-cut periods in the time course of ++anti-vascular antibody levels; for gestosis preclinical and clinical periods a constant growth of ++anti-vascular antibody titers was characteristics, that was due to effects of various injurious factors on the vascular wall. These data permit regarding gestosis as a vascular syndrome of pregnancy.


[Characteristics of thrombocyte metabolism in puerperae with massive blood loss and gestosis and possible ways of its metabolic correction].

Succinate dehydrogenase, phospholipid and glycogen activities were measured by cytochemical methods in puerperae with massive blood loss in the presence of gestosis in order to investigate platelet metabolism and the possible approaches to metabolic correction. A significant depression of platelet intracellular metabolism was revealed in these puerperae. Metabolic correction agents (acetyl salicylic acid, essential, alpha-tocopherol, retinol) were added to routine intensive therapy. The treatment was conducive to normalization of the metabolic processes and rapid recovery of puerperae with massive blood loss developing in the presence of gestosis.


[Effect of a new prostaglandin aroxaprostol on the contractile activity of the uterus and its abortive action in experimental studies].

Experiments with pregnant and nonpregnant rats have shown that aroxaprostol, a group F2 alpha prostaglandin, injected intravenously and intramuscularly in a dose of 50 micrograms/kg, stimulates the uterine bioelectric activity, increasing both the amplitude and frequency of biopotentials, this evidencing intensification of its contractility. Aroxaprostol has shown an abortive effect, that was related to the luteolytic effect of the drug, manifesting by reduction of progesterone level in the ovaries.


[Birth-related stress and postpartum adaptation of newborn infants after cesarean section].

The mechanisms of fetal and newborn adaptation to extrauterine life after normal and abdominal delivery were under study. Laboratory and instrumental methods were employed to examine the status of the intrauterine fetus and the clinical picture of the newborn adaptation in the early neonatal period: radioimmunoassays of dopamine, noradrenaline, adrenaline were carried out in fetuses and newborns after normal delivery and after cesarean section performed before and in labor. The results evidence that the adaptation shifts develop later in the newborns after cesarean section performed before labor than in those born spontaneously or by cesarean section that was performed in labor. The same tendency can be traced in the changes developing in the sympathoadrenal system. This result brings the authors to a conclusion that planned cesarean section should be performed after the onset of labor, if possible.


[Hormones of the adaptive-metabolic action in the menstrual cycle].

Triiodothyronine, thyroxine, thyrotropin, hydrocortisone, aldosterone, dehydroepiandrosterone, insulin, C peptide blood levels were radioimmunoassayed over the course of the menstrual cycle in healthy women aged 20 to 33. A relative stability of the thyrotropin-thyroid system was revealed, as were reduced levels of hydrocortisone and dehydroepiandrosterone and elevated content of insulin and aldosterone in the lutein phase of the cycle. The authors claim that these changes of the adaptation metabolic hormones are responsible for the psychoemotional and somatic status of women over the course of the cycle.


[Diagnostic and prognostic possibilities of using the indicators of blood serum middle molecule and medium-molecular peptide levels in inflammatory diseases of the small-pelvic organs].

Analysis of the diagnostic and prognostic potentialities of measurements of blood serum medium molecules and medium-molecular peptides in women with inflammatory diseases of the small pelvis organs has been carried out, involving 60 patients and 10 healthy women. Medium molecule levels were estimated with the use of Gabrielyan and Lipatova's method, the level of medium-molecular peptides by the biuret method. The results recommend these measurements to be included in the complex of clinical laboratory investigations carried out in patients with pelvic inflammations for the early detection of purulent ++tubo-ovarian inflammations, endogenous intoxication, and a more rational treatment.


[Individual prognosis of the risk of primary and secondary female infertility].

The authors suggest methodologic approaches to individual prediction of the risk of primary and secondary female sterility. A total of 512 women suffering from infertility were examined, and the major biomedical and ++socio-hygienic risk factors were detected. ++Socio-hygienic factors were found conducive to the development of biomedical factors or augmenting their effects. The Bayes' probability method and Wald's consecutive analysis underlie the developed system for prediction. Use of the prediction tables with due consideration for the results of medical examination of the patients helps more precisely define the group for prophylactic follow-up and give individual recommendations for medicosocial counselling.


[Epidural anesthesia with morphinomimetics in gynecologic operations].

Epidural anesthesia with injection of morphinomimetics into the epidural space was used in 181 patients during gynecologic surgery. The advantages of this type of anesthesia over the endotracheal one consist in reduction of the incidence of complications during the operation and after it.


[Diagnosis and control of the treatment of patients with precancerous conditions of the endometrium using transvaginal echography].

Twenty-six women aged 41 to 73 with clinical and morphologic forms of endometrial precancer were examined by transvaginal ultrasonic scanning. This method was employed both in the diagnosis and monitoring of the efficacy of hormone therapy. The final diagnosis was made on the basis of histologic examination of endometrial scrapings-off. The results evidence that transvaginal echography is a sufficiently informative method for the diagnosis of this condition and for monitoring the endometrial status over the course of hormonal therapy. The mean size of M-echo in the postmenopause was established: 2.35 +/- 0.07 mm in health or not imaged in endometrial atrophy. M-echo thickness of 11 +/- 0.02 mm may be indicative of the therapy inefficacy or endometrial hyperplasia, and the thickness of 8.7 +/- 0.7 mm indicates polyposis.


Analysis of oligosaccharides by on-line high-performance liquid chromatography and ion-spray mass spectrometry.

Oligosaccharides were analyzed by a combination of high-performance liquid chromatography (HPLC) and mass spectrometry (MS). First, oligosaccharides labeled with 2-aminopyridine were studied to see if they could be analyzed by MS under the conditions used for separation by HPLC. Pyridylamino (PA)-oligosaccharides could be analyzed under these conditions, although the mass spectra were affected. Then, liquid chromatography-mass spectrometry was used to analyze a PA-oligosaccharide mixture derived from human immunoglobulin G. The PA-oligosaccharides were separated on a reversed-phase column and mass-analyzed directly. The observed molecular weights were close to or identical to those expected from the structures, which were estimated from the elution position on HPLC. This method is rapid and simple, as the mass spectrometer can give the accurate molecular weight of each PA-oligosaccharide in one chromatography run, even if the HPLC separation is incomplete. This method can be used to extend the so-called two-dimensional mapping of PA-oligosaccharides. The structure can be studied in greater detail by tandem MS.


Construction of a thermotaxis chamber providing spatial or temporal thermal gradients monitored by an infrared video camera system.

A thermotaxis chamber was constructed to quantitatively study thermotaxis in eukaryotic amoeboid cells. The apparatus provided either spatial or temporal temperature gradients in an observation chamber set in an inverted microscope. With an infrared video camera system, spatial thermal gradients were monitored directly and the temperature at the actual location of the cells could be estimated accurately. This enabled a precise determination of the strength of thermal stimuli. With this apparatus, we were able to simultaneously measure temperature and observe cellular behavior directly. This feature permits quantitative studies on stimulus-response relationships. The utility of the apparatus was demonstrated by thermotaxis assay under a spatial thermal gradient in polymorphonuclear leukocytes. Since this apparatus can also provide temporal thermal gradients, it may have several applications in studies of temperature-dependent phenomena in cell biology.


Fluorescence probes in biochemistry: an examination of the non-fluorescent behavior of dansylamide by photoacoustic calorimetry.

Photoacoustic calorimetry is shown to be a simple, precise, and accurate method for the quantification of the photophysics of a fluorescence probe, e.g., dansylamide, in a variety of solvents. This technique, which is described in detail, provides a direct measurement of the energy that is released nonradiatively following photostimulation, and can therefore be used to indirectly determine the amount of energy released via luminescent pathways. Photoacoustic calorimetry combined with established absorption and fluorescence methodologies provides a complete arsenal for characterizing the photophysical properties of many systems. Comparison of the photoacoustic signal for dansylamide versus standard compounds (ferrocene, tetraphenylethylene, 8-anilinonaphthalene-1-sulfonate, and/or 5,5'-dithiobis(2-nitrobenzoic acid) in 12 different solvents gave fh values (fraction of each absorbed 337.1-nm photon returned as heat) from a low of 0.530 in 1,4-dioxane to a high of 0.973 in water. The trend noted with solvent polarity is different and more revealing than that determined by the more classical approach of examining either the wavelength of the emission maximum or the fluorescence quantum yield.


Gas-liquid chromatographic analysis of volatile short chain fatty acids in fecal samples as pentafluorobenzyl esters.

A protocol was developed for the analysis of volatile short chain fatty acids in microsamples of feces, short chain fatty acid (SCFA) extraction was from fecal samples using ethanol incorporating n-hexanoic acid as an internal standard. The SCFAs were converted to pentafluorobenzyl esters with alpha-2,3,4,5,6-pentafluorotoluene and analyzed on a gas-liquid chromatograph equipped with an electron capture detector. One hundred milligrams of sample was routinely used but analysis could be carried out on 20 mg of sample.


High resolution separation and quantitation of ribonucleotides using capillary electrophoresis.

A method for the analysis of ribonucleotides using capillary electrophoresis has been developed. A cross-linked polyacrylamide coated column, Tris-HCl, and phosphate-mixed buffer were used, which produced reproducible separations (solute migration time average RSD% of 1.2) of 14 ribonucleotides within 50 min. Linear relationships between peak areas and sample concentrations, an average minimum detectable concentration of 5.4 microM, and an average minimum detectable quantity of 0.08 pmol were obtained. The described method allowed reproducible and reliable qualitative and quantitative analysis of intracellular ribonucleotide pools in HeLa cells.


Resolution of dihydroxyeicosanoates and of dihydroxyeicosatrienoates by chiral phase chromatography.

A chromatographic method is described for the direct enantiomeric characterization of 5,6-, 8,9-, 11,12-, and 14,15-vic-dihydroxyeicosatrienoic acids (DHETs), metabolites of the cytochrome P-450 arachidonate epoxygenase pathway, and of their corresponding saturated vic-dihydroxyeicosanoic acids. Following esterification, the individual methyl or pentafluorobenzyl esters are resolved by chiral-phase chromatography utilizing a Chiralcel OC or OD column. This methodology will find analytical and preparative applications since it is simple and efficient and preserves, intact, the diol functionality.


Functionalized, probe-containing, latex nanospheres.

Synthesis of surface-functionalized, probe-containing latex nanospheres is described. Approximately 40,000 probe ions may be encapsulated in a nanosphere of 50 nm diameter. The probe may be a radionuclide or a lanthanide with long-lived fluorescence. Alternatively, a "cargo" of pharmaceutical interest may be used. The surface of each nanosphere contains thousands of acid groups which may be functionalized for subsequent attachment to biomolecules such as antibodies. Functionalized nanospheres have been successfully coupled to a tobacco virus.


Interference of the detergent Tween 80 in protein assays.

The nonionic detergent Tween 80, which has been widely used to stimulate protein secretion in bacterial and fungal systems, caused interferences in three protein determination methods. The OD595 developed in the Coomassie blue dye-binding assay with a variety of purified proteins in the presence of Tween 80 was 1.6 to 3.4 times greater than that observed without detergent. These differences could not be attributed totally to the rapid color development in the assay with Tween 80 alone. Crude concentrated extracellular bacterial proteins shaken overnight with Tween 80 yielded an altered fractionation pattern on size exclusion chromatography and 10-fold increased color with an absorption spectrum in the dye-binding assay different from that of bacterial proteins shaken without detergent. In the bicinchoninic acid method, the detergent caused a 2- to 3-fold increase in OD562 due largely to contaminating peroxides which could be removed by treatment with catalase. In the Folin phenol method, the detergent caused a slight precipitate, but residual interference was not detectable in filtered assay mixtures.


Application of the chemiluminescent assay to cytotoxicity test: detection of menadione-catalyzed H2O2 production by viable cells.

Menadione-catalyzed H2O2 production by viable cells is proportional to viable cell number. The correlations between the viable cell number and the concentration of H2O2 produced are determined with the rapid chemiluminescent assay (S. Yamashoji, T. Ikeda, and K. Yamashoji, 1989, Anal. Biochem. 181, 149-152). This chemiluminescent assay of viable cells requires only 10 min and is much faster than NR (neutral red) inclusion and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction assays, which require 3-5 h. When viable cells are incubated with antitumor drugs, detergents, mycotoxins, and glycoalkaloids for 24-48 h, a decrease in menadione-catalyzed H2O2 production in a dose- or incubation time-dependent manner is observed. In general, the 50% inhibition concentration determined by the chemiluminescent assay is lower than that determined by NR inclusion and MTT reduction assays, and the order of relative cytotoxic effects of agents is the same among these assays. Furthermore, clear cytotoxic effects are observed by the chemiluminescent assay after 1 h exposure of trypsinized cells to toxic compounds. Therefore, the chemiluminescent assay is expected to be more useful for the rapid detection of cytotoxic compounds than NR inclusion and MTT reduction assays.


Fluorescent rhodol derivatives: versatile, photostable labels and tracers.

A series of chemically reactive, fluorescent rhodol derivatives was prepared and evaluated. Reactive functional groups included activated esters, amines, haloacetamides, fixable hydrazide derivatives, acrylamides, and photoaffinity reagents. Depending on the choice of substituents, absorption maxima of the dyes varied from 490 to 550 nm with extinction coefficients that were generally greater than 50,000 M-1 cm-1 in aqueous solution and emission maxima from 520 to 580 nm. Most of the compounds investigated exhibited fluorescence lifetimes between 3 and 4 ns. Individual derivatives were suitable for excitation with the 488 and 514-nm lines of the argon ion laser and the 546-nm line of the mercury arc lamp and were compatible for use with standard fluorescein and rhodamine filter sets. The rhodol dyes were more photostable and less sensitive to pH changes in the physiological range than fluorescein derivatives. Some examples show absorption maxima at or near 514 nm, an excitation wavelength that is useful for multicolor fluorescence microscopy, flow cytometry, and DNA sequencing. Derivatives were also prepared that exhibit absorption and emission maxima similar to those of tetramethylrhodamine (TMR) analogs but with higher quantum yields in aqueous solution. A number of the dyes had higher solubilities in aqueous systems and were less quenched on conjugation to proteins than TMR derivatives. Appropriate substitution results in a wider range of solubilities in hydrophilic or lipophilic solvents than is easily accomplished with fluorescein or TMR derivatives. Conjugates of a number of the rhodol fluorophores were generally more photostable and less pH sensitive than fluorescein conjugates and more fluorescent than TMR conjugates.


A procedure for repeated usage of 33P-labeled DNA probes in hybridization experiments.

We describe a technique for repeated use of 33P-labeled DNA probes in Southern hybridization experiments. A nick-translated 33P-labeled DNA probe in a volume of 0.5-1.0 ml of hybridization mixture (final concentration, 10-100 ng/ml) is used to wet a sheet of filter paper (approx 10 microliters/cm2), which covers a nylon membrane with DNA transferred by Southern blotting, and both are set between two washed X-ray films. The "sandwich" is placed in a plastic bag for hybridization for 16-24 h at 42 degrees C. This very simple procedure using 33P-labeled DNA probes has a number of advantages over the standard method using 32P-labeled probes: (a) a significantly lower biohazard (body/arms exposure); (b) a very small volume of hybridization mixture in contact with a DNA-containing membrane and the higher probe concentrations attainable, causing some increase in sensitivity, and, finally, (c) repeated use of the probe-containing filter (over approx 3 days for unique sequences and up to 2 weeks for reiterated sequences) due to a relatively long 33P half-life (25.3 days).


Alkylation of cysteine with acrylamide for protein sequence analysis.

Alkylation of cysteine in proteins with acrylamide under mildly alkaline conditions yields a thioether derivative, Cys-S-beta-propionamide (Cys-S-Pam), which is stable during automated Edman degradation. Its phenylthiohydantoin derivative, PTH-Cys-S-Pam, is easily separated from other PTH-amino acids by HPLC and is thus useful for cysteine identification during protein sequencing. PTH-Cys-S-Pam was first noticed during sequencing polypeptides blotted onto polyvinylidene difluoride membranes from polyacrylamide gels, in which cysteine had reacted with residual unpolymerized acrylamide. Cysteine in proteins is easily alkylated by reaction of proteins in aqueous solution with acrylamide. Methods are also presented for alkylation of cysteine in proteins adsorbed on fiberglass disks in the reaction cartridge of a protein sequencer. Finally, PTH-Cys-S-Pam was synthesized chemically. The synthetic compound is unstable in neutral solution, but can be stabilized by acidification. It has the same HPLC retention time as the product formed from cysteine when sequencing proteins alkylated with acrylamide.