Schistosoma mansoni cercaria and schistosomulum antigens in serodiagnosis of schistosomiasis.

Schistosoma mansoni cercaria and schistosomulum obtained in vitro were used in immunofluorescence (IF) tests and indirect hemagglutination (IHA) tests of 137 study sera, 44 from subjects infected with S. mansoni and 93 from healthy subjects residing outside areas endemic for the disease. The results of these tests were compared with those obtained by testing the same sera using conventional adult worm antigen, and also with the initial clinical and parasitologic diagnoses of the 137 subjects providing the study sera. Regarding sera from acute versus chronic cases, IF testing of the acute sera consistently detected IgA antibodies along with IgM and IgG, the last two being found consistently in chronic sera. Also, the geometric mean of the IgM antibody titers found in the IF tests was higher for acute than for chronic sera. Excluding IF IgA, which was negative for chronic cases, the sensitivity of the other types of tests (IF IgG, IF IgM, and IHA) using cercaria and schistosomulum antigens, both under evaluation, ranged from 0.773 to 0.955, the specificity ranged from 0.957 to 1.000, the efficiency ranged from 0.927 to 0.985, the predictive value of positives ranged from 0.909 to 1.000, and the predictive value of negatives ranged from 0.903 to 0.979. No statistical differences were observed between these results and those obtained with conventional adult worm antigen. This suggests that cercaria and schistosomulum antigens, both of which can be produced more quickly and cheaply than adult worm antigen, could serve as reliable alternatives to adult worm antigen in the serodiagnosis of schistosomiasis mansoni.


Prevalences of tuberculosis and other respiratory diseases among people over age 15 in the northeast sector of Medellín, Colombia.

A survey was conducted in 1988 to estimate the prevalence of respiratory symptoms and pulmonary tuberculosis in people over age 15 in the Northeast Sector of Medellín, Colombia, an area suffering from severe socioeconomic depression. A cluster sample was selected for this purpose and 3,731 adults were interviewed in their homes. Those classified as respiratory symptomatics (ones reporting a cough lasting two weeks or more) were asked to provide samples for three sputum-smear examinations. The prevalence of pulmonary tuberculosis found in this survey was 2.68 cases per 1,000 subjects, a rate substantially greater than the prevalence of tuberculosis cases recorded in the Northeast Sector, and the prevalence of respiratory symptomatics was 70 per 1,000 subjects. Of eight subjects whose cases had been diagnosed previously, three said they had abandoned treatment. The prevalence of respiratory symptomatics was higher among poorly educated subjects and among those sleeping in poorly ventilated and/or overcrowded quarters. Overall, the survey data suggest that the tuberculosis control program in Northeast Medellín confronts a spectrum of problems ranging from low case-detection rates and high rates of abandoned treatment to social conditions and behavior patterns that foster host vulnerability and disease transmission.


Antimicrobial prophylaxis for fractured base of skull in children.

The details are reviewed of 50 children who were treated over a 10-year period with clinical signs of fractured base of skull. Two patients died early without signs of sepsis--due to the severity of their head injuries. Of the remainder, 23 received antibiotic prophylaxis and 25 did not. One patient from each of these groups developed pneumococcal meningitis, and they were successfully treated. Our results correlate well with those previously published, confirming the low incidence of infective complications with or without prophylaxis. The need to assemble a large enough series to make statistically significant conclusions regarding this infrequent condition is highlighted throughout the literature, which is reviewed here.


Asymmetrical brain modulation of the immune response.

It is now well known that the central nervous system can regulate the immune system. Interestingly the two sides of the brain have been demonstrated to be differently involved in the modulation of immune responses. In rodents, lesions of right or left neocortex induced opposite effects on various immune parameters including mitogen-induced lymphoproliferation, interleukin-2 production, macrophage activation or natural killer cell activity. Furthermore in humans, left-handedness has been reported to be associated with a high incidence of immune disorders. Likewise in mice, the direction of a lateralized motor behavior, i.e., paw preference in a food reaching task, correlated with an asymmetrical pattern of brain organization, was shown to be associated with lymphocyte reactivity, natural killer cell activity and auto-antibody production. Conversely the immune system could send to the brain information that may be asymmetrically expressed. The experimental models for investigating asymmetrical brain modulation of the immune system may be useful for studying physiological, pathological and genetic aspects of neuroimmunomodulation.


Neuroendocrine regulatory mechanisms in the choroid plexus-cerebrospinal fluid system.

The CSF is often regarded as merely a mechanical support for the brain, as well as an unspecific sink for waste products from the CNS. New methodology in receptor autoradiography, immunohistochemistry and molecular biology has revealed the presence of many different neuroendocrine substances or their corresponding receptors in the main CSF-forming structure, the choroid plexus. Both older research on the sympathetic nerves and recent studies of peptide neurotransmitters in the choroid plexus support a neurogenic regulation of choroid plexus CSF production and other transport functions. Among the endocrine substances present in blood and CSF, 5-HT, ANP, vasopressin and the IGFs have high receptor concentrations in the choroid plexus and have been shown to influence choroid plexus function. Finally, the choroid plexus produces the growth factor IGF-II and a number of transport proteins, most importantly transthyretin, that might regulate hormone transport from blood to brain. These studies suggest that the choroid plexus-CSF system could constitute an important pathway for neuroendocrine signalling in the brain, although clearcut evidence for such a role is still largely lacking.


Real-time display of flow-pressure-volume loops.

Graphic display of respiratory waveforms can be valuable for monitoring the progress of ventilated patients. A system has been developed that can display flow-pressure-volume loops as derived from a patient's respiratory circuit in real time. It can also display, store, print, and retrieve ventilatory waveforms. Five loops can be displayed at once: current, previous, reference, "ideal," and previously saved. Two components, the data-display device (DDD) and the data-collection device (DCD), comprise the system. An IBM 286/386 computer with a graphics card (VGA) and bidirectional parallel port is used for the DDD; an eight-bit microprocessor card and an A/D convertor card make up the DCD. A real-time multitasking operating system was written to control the DDD, while the DCD operates from in-line assembly code. The DCD samples the pressure and flow sensors at 100 Hz and looks for a complete flow waveform pattern based on flow slope. These waveforms are then passed to the DDD via the mutual parallel port. Within the DDD a process integrates the flow to create a volume signal and performs a multilinear regression on the pressure, flow, and volume data to calculate the elastance, resistance, pressure offset, and coefficient of determination. Elastance, resistance, and offset are used to calculate Pr and Pc where: Pr[k] = P[k]-offset-(elastance.V[k]) and Pc[k] = P[k]-offset-(resistance.F[k]). Volume vs. Pc and flow vs. Pr can be displayed in real time. Patient data from previous clinical tests were loaded into the device to verify the software calculations. An analog waveform generator was used to simulate flow and pressure waveforms that validated the system.(ABSTRACT TRUNCATED AT 250 WORDS)


Capacitive coupled stray currents during laparoscopic and endoscopic electrosurgical procedures.

Capacitively coupled currents may not be appreciated during laparoscopic and endoscopic radiofrequency electrosurgery. Two specific problems are documented and quantified: coupling of current into metal trocar cannulas during laparoscopic surgery and coupling of current into a guide wire during endoscopic surgery. The examples can yield power levels in excess of 25 watts (laparoscopic) and 15 watts (endoscopic) on nearby metal conductors, which can in turn be dissipated into patient organs such as the bowel or the common bile duct. This capacitive coupling can be, in part, responsible for serious patient complications. Methods to minimize capacitive coupling, e.g., active electrode shielding, dispersive metal cannulas, sheathed guide wires, and bipolar active electrodes, are discussed for each example.


Automated testing of arrhythmia monitors using annotated databases.

Arrhythmia-algorithm performance is typically tested using the AHA and MIT/BIH databases. The tools for this test are simulation software programs. While these simulations provide rapid results, they neglect hardware and software effects in the monitor. To provide a more accurate measure of performance in the actual monitor, a system has been developed for automated arrhythmia testing. The testing system incorporates an IBM-compatible personal computer, a digital-to-analog converter, an RS232 board, a patient-simulator interface to the monitor, and a multi-tasking software package for data conversion and communication with the monitor. This system "plays" patient data files into the monitor and saves beat classifications in detection files. Tests were performed using the MIT/BIH and AHA databases. Statistics were generated by comparing the detection files with the annotation files. These statistics were marginally different from those that resulted from the simulation. Differences were then examined. As expected, the differences were related to monitor hardware effects.


Dynamic image-adaptive x-ray beam limiters.

The imaging capability of the dynamic spatial reconstructor (DSR), a fast (60/second), synchronous, multislice (up to 240) computed x-ray tomography scanner, has been limited by the suboptimal match of the dynamic range of the x-ray projection images with that of the image-intensified charge-coupled device (CCD) video sensors. Effective blockage of the "raw" beam component of the projection images by fixed shutters is generally impossible because of the rapid change in the multiple angles of view that result from the 15 RPM rotation of the scanner assembly about the object of study. For this reason a programmable, dynamic, image-adaptive x-ray beam shutter system has been developed to reduce the "raw" beam component of the x-ray image without degrading the image in the region of interest. This system is designed to dynamically position 28 shutters (two for each of 14 x-ray sources) continuously and independently, as a function of the angle of view, so as to selectively obscure any unattenuated "raw" x-ray beam passing alongside the object of study at all angles of view for each x-ray source.


The Takeda Model UA-751 blood pressure and pulse rate monitor.

The performance of the Takeda Model UA-751 oscillometric blood pressure and pulse rate monitor was compared with readings taken using auscultatory technique and the mercury manometer. Significant correlations (p less than 0.0001) were found between the clinical standard and the UA-751 on measurements of systolic (r = 0.85) and diastolic (r = 0.77) blood pressure. Comparison of the pulse rate measurements obtained using the Grass Polygraph with those of the UA-751 resulted in a reliable correlation (r = 0.98; p less than 0.0001), as well. The results provide empirical support for the validity of the UA-751 under controlled laboratory conditions. However, the results suggest heightened error in the measurement of systolic pressure when the UA-751 is used by individuals who have high blood pressures.


The measurement of radiant temperature in neonatal thermal environments.

Heat exchange through radiation is recognized as the dominant mode of heat transfer for an infant nursed in an incubator or warmer. A radiometer was constructed to measure the planar radiant temperature experienced by the infant. Two heat-flow sensors of different emissivities were mounted onto a heat sink such that one measured principally convective heat exchange while the other measured convective and radiant heat exchange. The radiant heat exchange was obtained from the difference between these values, from which the planar radiant temperature could be calculated. The spatial variation in planar radiant temperatures within an incubator and warmer was determined by orienting the instrument towards the five orthogonal hemispheres sensed by the infant abdomen, sides, head, and feet. In the incubator, the spatial variation in radiant temperatures exceeded 2 degrees C, or four times the spatial variation in air temperatures (0.5 degrees C). The radiant warmer had a spatial variation of 18 degrees C in radiant temperature at three-fourths of maximum power, corresponding to a variation in heat flux over the infant's surface of 100 W/m2. This thermal asymmetry would be expected to influence the variation in surface skin temperature, and thus the thermal stimuli to the infant thermoregulatory system. Further research is needed to understand the clinical significance of this asymmetry. Furthermore, the precise control over air temperature in modern incubators provides a false sense of thermal control and stability. Radiant temperature needs to be measured in addition to air temperature if the thermal performances of incubators and warmers are to be fully understood.


A system for in-vitro characterization of heart valve bioprostheses under accelerated fatigue conditions and under physiologic conditions.

An accelerated fatigue testing system and a pulse duplicator (heart simulator) were used in a set-up in which pressure differences and pulsatile flow rates across prosthetic heart valves, as well as machine rates, could be measured using a real-time on-line data-acquisition system. With this information available, an immediate in-vitro characterization of the fluid dynamics of prosthetic heart valves could be obtained under both physiologic and accelerated conditions. In addition to the fatigue tester and the pulse duplicator, a signal conditioner, a DC amplifier, an analog-to-digital converter, and a digital microcomputer comprised the essential hardware. For the purpose of this study, special acquisition software was developed. By means of the same computational algorithms, all quantitative fluid dynamics data could be calculated using information from both the pulse duplicator and the fatigue tester, so that direct comparisons and correlations could be approached. Pressure difference-flow rate relationships for the two machines were comparable.


The quest for better validation: a critical comparison of the AAMI and BHS validation protocols for ambulatory blood pressure measurement systems.

Two validation procedures are currently available for the evaluation of ambulatory blood pressure measurement systems--the standard of the Association for the Advancement of Medical Instrumentation (AAMI) and the protocol of the British Hypertension Society (BHS). Both are in the process of revision. Four systems for measuring 24-hour ambulatory blood pressure--SpaceLabs 90207, Novacor DIASYS 200, Del Mar Avionics Pressurometer IV, and Takeda TM-2420--were evaluated according to the BHS protocol, which incorporates many of the features of the AAMI standard, under similar conditions by the same personnel and in the same subjects, so as to examine the relative merits of the two evaluation procedures. Three recorders of each model were subjected to a before-use inter-device variability test, followed by an in-use phase and an after-use inter-device variability test. The main validation test was carried out in 86 subjects with a wide range of pressures, the results being analyzed according to the BHS grading system and the AAMI validation criteria. The SpaceLabs 90207 and the DIASYS 200 achieved B and C grades, respectively, according to the BHS protocol and also satisfied the AAMI criteria for accuracy. The Pressurometer IV achieved a Grade C rating for systolic pressure and a Grade D rating for diastolic pressure and the Takeda TM-2420 achieved Grade D ratings for both systolic pressure and diastolic pressure. Both these devices failed to fulfil the AAMI criteria for accuracy and both failed to function in the main validation test and had to be replaced.(ABSTRACT TRUNCATED AT 250 WORDS)


Thermal profiles of electrocauteries, the Nd:YAG laser, and the electromagnetic-field focusing system.

Electromagnetic-field focusing (EFF) is a method of converging induced eddy current onto a pointed tip of a tuned length return circuit in the near field of a resonator, which results in the production of high temperature. Previously reported applications of this method include various devices for local hyperthermia and a precision surgical device. The latter is currently being used in human clinical trials under two investigational device exemptions from the Food and Drug Administration. In the present work, the thermal profile produced in a uniform, tissue-simulating phantom by the hand-held probe of the surgical EFF system is compared with those produced by mono- and bipolar electrocauteries and by a contact Nd:YAG laser. At the equivalent power setting and 2-cm insertion depth, the EFF probe was shown to have a tighter thermal profile than the monopolar electrocautery or the contact Nd:YAG laser. This finding is consistent with earlier histologic evidence that brain cortical tissue cut by the surgical EFF probe had minimal thermal damage in the tissue surrounding the incision.


Current treatment of ulcerative colitis.

Ulcerative colitis is a chronic relapsing disease which may become manifest either early or late in life. This article examines current drug treatment strategies and considers possible therapeutic options for the future.


Physiological consequences of complete cardiac denervation.

The transplanted human heart remains functionally denervated for 5 or more years postoperatively. Denervation has a number of implications for cardiac function, not the least of which is the inability of transplant recipients to experience ischaemic pain. The study of the denervated heart has not only shed light on the physiology of cardiac transplantation but also provided further insights into the functioning of the normally innervated heart.


Boring arteries: television and tubes, a new peripheral vascular surgery?

Modern methods of recanalizing occluded peripheral blood vessels essentially began with various endarterectomy techniques. However, apart from carotid endarterectomy, none has made a lasting impact, mainly due to poor long-term patency.


Inhaled anaesthetic agents: from halothane to the present day.

Despite the enormous resources spent on research and development, only two new volatile agents have been introduced into anaesthetic practice in the UK since the introduction of halothane. This article reviews their properties and looks towards changes in volatile anaesthetic availability in the near future.


Haematological and immunological abnormalities in eating disorders.

Eating disorders are associated with a wide range of physical symptoms and signs and with aberrant laboratory findings. The frequency of haematological and immunological abnormalities reflects the key role of adequate nutrition in the maintenance of normal bone marrow and immune function. The nature of these abnormalities and their clinical implications are discussed here.


Clinical exams: interviewing in front of examiners.

The re-examination of a patient in front of two examiners is a major part of the clinical exams in psychiatry. However, for the candidate it is the most anxiety-provoking part of the exam, and possibly the area of greatest weakness.


Cannon balls.

Radiological terminology includes a number of interesting and often amusing terms intended to help us understand and remember the pathological abnormality being described. What radiological sign is illustrated in Fig. 1 and what is the differential diagnosis?


Seasonal affective disorders.

The recurrent nature of mania and depression has led to a search for factors that might predict the timing of episodes. There has recently been a resurgence of interest in the possibility that seasonal changes may precipitate affective illness.


Management of acute myeloid leukaemia.

Advances in the management of acute myeloid leukaemia have led to an improvement in survival from what was invariably a fatal disease. This review presents some of these advances and outlines the modern management of this condition.


Rheumatology and the gut.

Some conditions may present with gastrointestinal and rheumatological manifestations. Salmonella osteomyelitis results from direct infection of bone following gut infection and bacteraemia, but in other conditions the pathogenesis is less clear. There may be a microbial cause for rheumatoid arthritis; however, this theory remains unproven.


A guide to lung function tests.

In patients with respiratory disease, measurement of lung function should be part of the assessment if possible. In the ward, clinic and lung function laboratory there are tests available to examine airflow, lung volume, gas transfer and exercise capacity. These provide information on lung function which may be vital for adequate diagnosis and assessment of the patient.


Heterosexual transmission of human immunodeficiency virus.

Heterosexual human immunodeficiency virus (HIV) transmission accounts for most cases of HIV infection and acquired immunodeficiency syndrome worldwide. Moreover, in the developed world the proportion of individuals infected heterosexually is rising faster than the proportion infected by other routes, with an increase in the number of women infected. Defining the factors associated with heterosexual transmission may help control new infections.


Guide to postgraduate exams: how to prepare.

Ways in which doctors might learn, revise and prepare for postgraduate exams are outlined in this article. Some educational principles are described to explain why understanding is far more useful and permanent than rote-learning. Suggestions are also made about exam technique.


Monitoring of cerebral function.

The cerebral function of sedated ventilated patients cannot be assessed by neurological examination, yet many of these patients may have changing cerebral function which needs urgent treatment. Many methods of measuring cerebral function are available and are reviewed in this article along with recommendations for practical monitoring within the intensive care unit.


Ten-digit and nine-digit replantation (4 cases).

Ten or nine-digit amputation is a very rare injury. From March, 1987 to June, 1988, we replanted two cases of ten-digit complete amputation and two cases of nine-digit complete amputation with success. The maximum ischaemic time was 39 h and the operation time was between 25 and 31 h. All digits survived completely except for partial necrosis of one finger. The follow-up has been 13-20 months, and all the patients have a pair of good, functional and aesthetically acceptable hands.


Tissue expanded free flaps.

Over the last few years there have been various reports of the use of tissue expanders as an adjunct to microvascular free transfer of tissue. This study looks at the effect of expanding the actual flap prior to transfer. Two case reports are given and it is proposed that expanded free flaps are large and thin. They have a capsule which enables them to be safely sutured under tension. They are "delayed" by the expansion process and the donor deformity is minimal. It is suggested that tissue expansion is a useful technique prior to free flap transfer for the reconstruction of large defects.


Thromboembolic prophylaxis in plastic surgery: an appraisal.

A survey by questionnaire was conducted amongst consultant plastic surgeons in the UK: 54 replies were received (44% response rate). Three consultants (5.5%) never used any form of DVT prophylaxis. The other 51 (94%) used some form of prophylaxis in at-risk patients. The methods used were found to be diverse. Ten respondents belonged to units with fixed policies for prophylaxis. A controlled trial is suggested to provide statistical evidence of the need for thromboembolic prophylaxis among plastic surgical patients. We believe there is a need for units to develop fixed protocols for the prevention of thromboembolism in at-risk patients.


A computerised machine for the facilitated production of intermingled skin grafts.

The introduction of intermingled allograft/autograft skin grafting in western countries has long been hampered by high costs, due to the personnel requirements to produce this special form of graft. We have solved this problem by designing and constructing a computer-controlled machine, which in one operation punches holes out of strips of allogeneic donor skin and in another cuts fitting islets out of autogenous skin and transfers them into these holes. In comparison to manual preparation, this machine not only accelerates the production of intermingled skin grafts, but it also inserts the islets with superior accuracy, which is very important for the final functional and cosmetic result.


The surgical management of dystrophic epidermolysis bullosa (excluding the hand).

Fifty patients with Dystrophic Epidermolysis Bullosa (DEB) underwent surgery including release of limb, oral, anal, eye and penile contractures and treatment of chronic skin ulceration or skin tumours. Correction of contractures involves extensive release of skin and underlying tissues, with split skin grafting of secondary defects. Specific regions are discussed. Recurrence is inevitable due to ongoing disease; however, functional improvement is obtained for several years. Management of chronic skin ulceration with split skin grafting has failed to produce long term healing, with local flaps successful but limited by the problem of donor site instability. Nine of the 17 patients over 20 years of age developed squamous cell carcinomas (29 lesions), benign hyperkeratosis (9) or malignant melanoma (1) requiring excision and skin grafting or amputation of digits. Local recurrence was infrequent (3 squamous cell carcinomas), with distant metastatic spread occurring in 1 patient.


A versatile method for reconstruction of finger defects: reverse digital artery flap.

Four types of the reverse digital artery flap--standard, extended, and innervated standard and extended--were developed for 52 finger defects. The arising pattern of the dorsal branch which was included in the innervated flap was studied and classified in cadaver dissections. Topographically, the described "Lai's line" is a useful guide to locate the underlying digital artery. Refinements in flap design and surgical technique resulted in favourable functional and cosmetic results. The average two-point discrimination of the reconstructed fingertip was 6.8 mm and 3.9 mm in the noninnervated and innervated flaps, respectively. This versatile flap is an ideal and reliable option for one-stage reconstruction of various finger defects.


Medial Langenbeck: experience of a modified Von Langenbeck repair of the cleft palate. A preliminary report.

Early experience of a modified Von Langenbeck repair of cleft palate is reported. In each case the traditional method of repair has been adopted, but with the relieving incision placed medial to the greater palatine artery. Out of a total of 40 patients over a 2-year period 8 were noted to have a fistula, of which 4 closed spontaneously, leaving 4 (10%) potentially requiring further surgery. The modified oral layer closure was conceived with muscle repair directed at restoring normal anatomy and concentrating on construction of a median dorsal convexity.


Morbidity after gold weight insertion into the upper eyelid in facial palsy.

Morbidity and outcome after gold weight insertion into the upper eyelid in patients with lagophthalmos were assessed retrospectively by patient questionnaire and case-note review. Results indicated that although satisfaction with the lid and overall facial appearance was high, complications and symptoms attributable to the gold weights were not uncommon.


The relationship between prostaglandin E1 applied area and flap survival rate.

Using a silicone gel sheet continuous drug delivery system containing Prostaglandin E1 (PGE1), the relationship between flap survival rate and the site of drug application was studied. Skin flaps measuring 2 x 9 cm were raised on the dorsum of rats, and divided into 3 areas. Area 1 was within 3 cm of the flap tip, area 2 was between 3-6 cm from the flap tip including the critical zone, and area 3 was the portion within 4 cm of the flap base. Further, area 4 was a strip of skin around the flap, 1 cm in width. Compared to the control group, a significant increase in flap survival rate was seen only when PGE1 was administered to area 2 (p < 0.01, t-test). Specimens injected with dye intravascularly showed an increase in the number of thick vessels in area 3, when PGE1 was applied only to area 3. However, when PGE1 was applied to area 2, there was no significant vascular increase in area 3. Instead, an extensive network of fine vessels was observed in area 2.


Pneumosinus dilatans as the aetiology of progressive bilateral blindness.

Pneumosinus Dilatans is a rare condition of the craniofacial skeleton which was diagnosed in an adolescent male who presented with progressive bilateral blindness and many features of osteodysplasty (Melnick-Needles Syndrome). The clinical course and unusual pathology of this case which included the compression of both optic nerves within long tubes of bone are described, together with the surgical intervention performed to arrest the patient's loss of vision.


A vascularised periosteal flap: anatomical study.

Twenty-seven anatomical studies were done to elucidate the periosteal blood supply on the lateral surface of the shaft of the tibia. The dissection of a vascularised periosteal flap is described. The applications of this flap are discussed in the light of previous clinical and experimental reports on periosteal flaps and a successful clinical case is detailed. This flap has application for electively treating bony non union. It may also be used as a free flap in an acute trauma situation involving bone loss.


Transcutaneous extravasation of silicone following breast augmentation.

Transcutaneous leakage of silicone in the absence of sinus formation has not previously been described. We present a case in which silicone extravasation occurred following the rupture of a breast implant inserted 14 years previously.


Necrotising fasciitis in the head and neck region.

Necrotising fasciitis is an uncommon entity in present day medicine. Our review of the literature did not reveal any case involving the head and neck region. A case of this rare disease involving the head and neck region is presented.


Syringe suction drain.

A mini suction drain made up of a 20 cc glass syringe, a stainless steel spring and a scalp vein cannula (whose needle end has been cut off and multiple holes made in the distal 2.5-5 cm) is described. It is very useful in preventing postoperative haematoma formation, in nasogastric tube suction, in easy drawing up of fluids from vials, and in exploration of deep seated abscesses and collections. It is inexpensive, as syringe and spring can be re-used after sterilisation by autoclaving.


Evidence that the apparent complexity of receptor antagonism by angiotensin II analogues is due to a reversible and syntopic action.

1. The interactions between angiotensin II (AII), two non-peptide antagonists DuP 753 and IMI, and eight peptide analogues of AII were investigated on the rabbit isolated aorta assay. DuP 753 and IMI behaved as simple competitive antagonists (pKB values 8.4 and 6.8, respectively). To different degrees, all the AII-peptide analogue interactions failed to meet the basic criteria for simple competition. In addition to rightward shift, the most significant feature was a concentration-dependent saturable depression of the upper asymptote of the AII concentration-effect curves. 2. 'Washout' and combined dose-ratio analysis experiments, in which DuP 753 was used as a reference antagonist, indicated that the profile of peptide antagonism was solely due to a reversible and syntopic action at the AII receptor. 3. By use of an operational model of agonism (Black & Leff, 1983) as a starting point, it was possible to account for the data with a new model which describes reversible receptor occupancy and occupied receptor-determined, saturable reduction in the efficacy of AII. Model-fitting gave estimates of pKB values for the peptide analogues and agonist affinity and efficacy parameters for AII. 4. The model was successfully tested by applying it to qualitatively similar results obtained in a cross-tissue analysis on guinea-pig aorta, ileum and stomach. 5. A 'molecular' interpretation of the efficacy changes, based on the concepts of receptor internalisation and expression, is offered.


Effect of the hypoglycaemic drug (-)-AZ-DF-265 on ATP-sensitive potassium channels in rat pancreatic beta-cells.

1. It has previously been shown that the hypoglycaemic drug (-)-AZ-DF-265 stimulates insulin release from mouse islets; in the presence of 3 mM glucose it also inhibits 86Rb-efflux from 86Rb-loaded islets. Based on these data we tested the hypothesis that (-)-AZ-DF-265 inhibits ATP-sensitive potassium channels. 2. We voltage-clamped the plasma membrane of single rat pancreatic beta-cells in the whole-cell configuration and measured the current flowing through ATP-sensitive potassium channels. (-)-AZ-DF-265 was applied to the outside of the cell; it inhibited the current half-maximally at a concentration of 1.2 +/- 0.2 nM with a Hill coefficient of 0.7 +/- 0.1. The inhibition was reversible on washing. 3. In intact RINm5F cells, the sulphonylurea [3H]-glibenclamide bound with an affinity of 0.24 +/- 0.01 nM and a Hill coefficient of 2.1 +/- 0.4. Treatment with (-)-AZ-DF-265 led to the displacement of [3H]-glibenclamide; this effect was half-maximal at 8.6 +/- 1.7 nM and displayed a Hill coefficient of 0.53 +/- 0.01. Meglitinide and tolbutamide, which represent, respectively, the benzamido and sulphonylurea moieties of glibenclamide, showed Hill coefficients of 0.8 +/- 0.1 and 0.9 +/- 0.1, respectively. 4. At pH 7.4 and with phosphate/borate buffer, (-)-AZ-DF-265 had an apparent octanol/water partition coefficient of about 53, which is intermediate between the partition coefficients of glibenclamide and glipizide. Nevertheless, (-)-AZ-DF-265 bound only to a minor degree to glass and plastic.5. In conclusion, (-)-AZ-DF-265 inhibits ATP-sensitive potassium channels and displaces [3H]-glibenclamide from the sulphonylurea receptor.


Platelet activating factor and systemic anaphylaxis in Nippostrongylus brasiliensis-sensitized rats: differential effects of PAF antagonists.

1. The effects of two platelet-activating factor (PAF) antagonists, WEB 2086 and BN 52021, in reducing the changes in extravasation (Evans blue technique) and blood flow (radiolabelled microsphere method) to various organs and tissues following anaphylactic shock in the Nippostrongylus brasiliensis-sensitized rat were investigated. 2. Both antagonists attenuated anaphylaxis-induced increases in plasma protein leak in the trachea, stomach and small intestine, although they did not block extravasation in the colon and kidneys. 3. Anaphylaxis-induced decreases in blood flow to the adrenals were effectively antagonized by WEB 2086, although this antagonist did not reverse blood flow decreases to any other tissues. BN 52021, on the other hand, did not alter anaphylaxis-induced decreases in blood flow to the adrenals, but effectively prevented dramatic decreases in blood flow to the large and small bowel and spleen. 4. Anaphylactic shock produced marked reduction in blood pressure that was partly reversed by WEB 2086, whereas BN 52021 effectively blocked the decreases in cardiac output. 5. Thus, PAF is responsible for some of the haemodynamic and extravasation of protein changes associated with systemic anaphylaxis in the rat, although the differential inhibition observed with the two antagonists suggests that PAF alters vascular responsiveness through different mechanisms in selected tissues.


Functional comparisons of gastrin/cholecystokinin receptors in isolated preparations of gastric mucosa and ileum.

1. The gastrin cholecystokinin (CCK) receptors mediating stimulation of acid secretion in rat isolated gastric mucosa (RGM) and contraction in guinea-pig isolated ileum longitudinal muscle-myenteric plexus (GPI) have been characterized by use of peptide agonists and the non-peptide antagonists, lorglumide, devazepide and L-365,260. 2. In RGM, gastrin peptides (sulphated gastrin heptadecapeptide (G-17), non-sulphated (ns) G-17 and pentagastrin) were potent agonists of acid secretion (EC50 values of 4.3, 16 and 27 nM respectively). Sulphated CCK octapeptide (CCK-8) was also a potent agonist, (EC50 = 0.9 nM), but was less efficacious, producing a lower maximal response. In contrast, in GPI, CCK-8 was a potent full agonist (EC50 = 1.4 nM) and was more than 1000 times more potent than the gastrin peptides in producing a sustained contractile response. 3. In GPI, CCK-8 (0.1 to 100 nM) produced sustained contractile responses, whilst CCK-4 (3 to 1000 nM) produced transient responses. These responses had different sensitivities to atropine (1 microM), suggesting that more than one receptor may mediate contraction in this tissue. 4. In RGM, L-365,260 was the most potent antagonist of pentagastrin-stimulated acid secretion (pA2 = 7.6). This functional affinity estimate was similar to that for L-365,260 as an antagonist of excitatory responses in rat ventromedial hypothalamic slices (Kemp et al., 1989) but differed from binding affinity estimates in guinea-pig cortex and gastric glands (Freidinger, 1989). 5. In GPI, devazepide, L-365,260 and lorglumide yielded different affinity estimates when compared against CCK-8 and CCK-4 or pentagastrin respectively.These studies were consistent with the view that the sustained response produced by CCK-8 was mediated by CCKA receptors and the transient response produced by CCK-4 and pentagastrin was mediated by CCKB receptors.6. Affinity estimates for L-365,260 and lorglumide against CCK-4 or pentagastrin in GPI were significantly different from corresponding estimates against pentagastrin in RGM. These studies are consistent with the view that gastrin/CCKB receptors in GPI may differ from those in RGM.


Effect of MgATP on pinacidil-induced displacement of glibenclamide from the sulphonylurea receptor in a pancreatic beta-cell line and rat cerebral cortex.

1. The effects of blockers and openers of K+ channels on binding of [3H]-glibenclamide to microsomes obtained from a pancreatic beta-cell line (HIT-T15) or rat cerebral cortex were examined. 2. The blockers quinine, chlorpromazine and thiopentone and the openers cromakalim [(+/- ) 6-cyano-3,4-dihydro-2,2-dimethyl-trans-4-(2-oxo-1- pyrrolidyl)-2H-benzo[b]pyran-3-ol] and minoxidil sulphate did not significantly interact with the sulphonylurea receptor of HIT-cells both at phosphorylating (presence of MgATP) and dephosphorylating (absence of MgATP) conditions. 3. In the absence of MgATP, pinacidil (200-500 microM) did not significantly displace [3H]-glibenclamide binding to microsomes from HIT-cells. The displacement of [3H]-glibenclamide binding was strongly enhanced by MgATP and was due to a decrease in the number of high affinity binding sites for glibenclamide. 4. MgATP enhanced pinacidil-induced inhibition of [3H]-glibenclamide binding to microsomes from rat cerebral cortex. 5. The effect of MgATP on pinacidil-induced inhibition of [3H]-glibenclamide binding was maintained after solubilization of the membranes from HIT-cells or rat cerebral cortex. 6. It is concluded that the sulphonylurea receptor is regulated not only by sulphonylureas but also by the K+ channel openers, diazoxide and pinacidil, and by protein phosphorylation. The binding sites for sulphonylureas and these K+ channel openers are not identical, but appear to be located at a single protein or at tightly associated proteins.


Effects of BRL 38227, sodium nitroprusside and verapamil on collateral perfusion following acute arterial occlusion in the rabbit isolated ear.

1. We have used an isolated, buffer-perfused, rabbit ear model of acute arterial occlusion to investigate the effects of the nitrovasodilator sodium nitroprusside, the potassium channel activator BRL 38227 (the active (-)-enantiomer of cromakalim) and the calcium antagonist, verapamil, on collateral perfusion in the absence of pharmacological tone. 2. Verapamil was the most potent vasodilator (EC50 = 72.6 +/- 32.0 nM) of 5-hydroxytryptamine/histamine-induced tone in the rabbit isolated perfused ear. Sodium nitroprusside and BRL 38227 were less potent with respective EC50 values of 488 +/- 75 nM and 296 +/- 40 nM. Following inhibition of endothelium-derived relaxing factor (EDRF) synthesis, the potency of BRL 38227 was significantly (P less than 0.001) increased with an EC50 of 55.6 +/- 5.0 nM. 3. BRL 38227 at 500 nM and 3 microM induced substantial increases in collateral perfusion following arterial ligation in the absence of pharmacological tone compared to control. Furthermore 3 microM BRL 38227 completely reversed the attenuation of collateral perfusion which followed inhibition of EDRF synthesis with 100 microM NG-nitro-L-arginine methyl ester (L-NAME). 4. Sodium nitroprusside (500 nM and 3 microM) induced modest improvements in collateral perfusion in the early stages after arterial occlusion. 5. Verapamil did not influence collateral perfusion at either of the concentrations used (50 nM and 3 microM), even though it was a potent vasodilator. 6. The results of this study indicate that BRL 38227, and to a much lesser extent sodium nitroprusside, selectively improve collateral perfusion following arterial occlusion, even in the presence of effects of EDRF on acute collateralization, while verapamil has no effect. Furthermore, BRL 38227 also improves collateral perfusion following inhibition of EDRF synthesis. It remains to be established whether BRL 38227 has beneficial actions in acute arterial occlusion in vivo.


Developmental changes in endothelium-dependent pulmonary vasodilatation in pigs.

1. We compared in vitro endothelium-dependent vasorelaxant responses to acetylcholine (ACh) and the endothelium-independent vasodilator response to sodium nitroprusside (SNP) in prostaglandin F2 alpha (PGF2 alpha)-precontracted muscular pulmonary arteries (PA) from pigs aged 5 min to 2 h (neonatal), 3-10 days, 3-8 weeks and adults. 2. In the pulmonary artery (PA) rings from neonatal animals, the vasodilator response to ACh was negligible. However, responses to ACh were present in all PA rings from older animals, being greatest at 3-10 days and then decreasing with age (P less than 0.001, ANOVA). ACh (30 microM) induced a 1 +/- 1%, 92 +/- 9%, 62 +/- 5% and 51 +/- 6% reduction of the PGF2 alpha-generated tension in neonatal, 3-10 days, 3-8 weeks and adult groups, respectively. 3. The relaxant response to SNP was present in the PA rings from all age groups and increased with age (P less than 0.001, ANOVA). SNP (1 microM)-induced relaxation was 55 +/- 9%, 73 +/- 7%, 97 +/- 5% and 93 +/- 6% in neonatal, 3-10 days, 3-8 week and adult groups, respectively. 4. Removal of the vascular endothelium abolished the relaxant response to ACh but had no effect on the response to SNP in any groups. 5. NG-monomethyl-L-arginine (30 microM), a nitric oxide synthesis inhibitor, inhibited the response to ACh but not to SNP. The lipoxygenase inhibitor, nordihydroguaiaretic acid, had no significant effect on responses to ACh or SNP in any group.6. These findings suggest that the nitric oxide pathway may not play a part in dilating the pig pulmonary arteries at birth, but may be important during the transitional period of establishing a stable post-natal pulmonary circulation. The increase in response to SNP with age parallels the increase in smooth muscle cell myofilaments to which it may be related.


Pituitary adenylate cyclase activating polypeptide is a potent vasodilator and oedema potentiator in rabbit skin in vivo.

1. The effects of pituitary adenylate cyclase activating polypeptide (PACAP) on microvascular blood flow and plasma protein leakage were investigated in rabbit skin in vivo. 2. Intradermal injection of PACAP38, the 38 amino acid form of the peptide, caused a dose-dependent increase in blood flow measured by a 133Xe clearance technique. An equivalent increase in blood flow was induced by 10(-12) mol per site of PACAP38, 10(-12) mol per site of human alpha-calcitonin gene-related peptide (CGRP) and 10(-10) mol per site of vasoactive intestinal polypeptide (VIP). 3. The vasodilator activity of PACAP38 was not significantly different from that of the 27 amino acid form of the peptide, PACAP27, when measured with a laser Doppler flow meter, causing a 104 +/- 14% compared with 110 +/- 18% increase above basal blood flow at 10(-12) mol per site respectively. 4. At 10(-12) mol per site the effect of PACAP38 was longer lasting than that of CGRP. Blood flow remained significantly increased above control at 2 h with PACAP38 (P less than 0.05) whereas blood flow after intradermal CGRP had returned to control values by this time. 5. PACAP38 injected alone had no significant effect on microvascular leakage of 125I-labelled albumin. However, PACAP38 significantly potentiated bradykinin-induced oedema where it was approximately 100 fold more potent than VIP. 6. Oedema potentiation induced by PACAP38 was not inhibited by indomethacin at a dose which did inhibit potentiation of bradykinin-induced oedema by arachidonic acid.7. PACAP38 is at least as potent as other peptides which have been postulated to be involved in the inflammatory response when tested in rabbit skin in vivo. PACAP may contribute to both the hyperaemia and oedema components of inflammation.


Purinoceptors mediating relaxation and spasm in the rat gastric fundus.

1. The relaxant and spasmogenic effects of purines and analogues were studied in longitudinal strips of rat gastric fundus to characterize the purinoceptors involved. Classification was studied by use of agonist potency orders and of antagonists in circumstances where the influence of confounding factors was reduced. In general tone was raised by carbachol (0.1 microM). 2. Adenosine produced relaxation and was potentiated by nitrobenzylthioinosine (NBTI, 0.3 and 30 microM), an adenosine-uptake inhibitor. 8-Sulphophenyl-theophylline (8-SPT, 30 microM), a selective P1-purinoceptor antagonist, antagonized adenosine and 5'-N-ethylcarboxamidoadenosine (NECA), a selective agonist at P1-purinoceptors. 3. At resting tone, adenosine 5'-triphosphate (ATP) induced a small, phasic relaxation followed by a maintained spasm. When tone was raised by carbachol, ATP induced a larger relaxation followed by a smaller spasm. NBTI did not potentiate ATP, nor did 8-SPT antagonize ATP, suggesting that ATP does not act directly or indirectly at P1-purinoceptors. 4. With raised tone, and in the presence of indomethacin (10 microM) and 8-SPT (30 microM), 2-methylthio ATP (2-MeSATP) and ATP produced relaxations followed by spasms while alpha,beta-methylene ATP (alpha,beta-MeATP) induced only relaxation; all responses were concentration-dependent. The compounds had similar slopes and maxima for relaxation and spasm. The rank orders of potency were 2-MeSATP much greater than alpha,beta-MeATP greater than ATP for relaxation and 2-MeSATP much greater than ATP for spasm.5. With raised tone, and in the presence of indomethacin and alpha 8-SPT, desensitization to alpha,beta-MeATP (100microM) completely and only slightly suppressed responses to ATP and 2-MeSATP, respectively, as relaxants but had no effect on relaxant responses to adenosine. The magnitude of the spasms to ATP and 2-MeSATP was considerably increased by desensitization with alpha,beta-MeATP but the spasm to KCl was not affected.6. With raised tone, and in the presence of indomethacin and 8-SPT, reactive blue 2 (10 AM) nonselectively antagonized ATP, 2-MeATP, a,P-MeATP, adenosine and isoprenaline as relaxants. Reactive blue 2 prevented the spasms to ATP and 2-MeSATP but not spasm to KC1.7. With raised tone, and in the presence of indomethacin, suramin (100 microM) antagonized ATP, but not adenosine, as relaxants and antagonized ATP, but not KC1, as spasmogens.8. It is proposed that adenosine is susceptible to nucleoside-specific uptake and acts predominantly via a P,-purinoceptor and also by a non-PI-purinoceptor mechanism. ATP- and alpha,beta-MeATP-induced relaxations probably occur via a P2x-purinoceptor. The anomalous nature of the 2-MeSATP-induced relaxation suggests it acts both via a P2x-purinoceptor and an additional mechanism. A P2y-purinoceptor is most likely to be involved in the spasms to ATP and 2-MeSATP. Therefore, the functional nature of the responses mediated by P2X- and P2y-purinoceptors, relaxation and spasm respectively, are opposite to those seen in most smooth muscles.


Nitric oxide and relaxation of pig lower urinary tract.

1. We studied the non-adrenergic, non-cholinergic (NANC) nerve-mediated relaxation induced by electrical stimulation in pig isolated lower urinary tract smooth muscle, and the possible involvement of the L-arginine (L-ARG)/nitric oxide (NO) pathway in this response. 2. Trigonal strips, precontracted by noradrenaline (NA), carbachol or endothelin-1 (ET-1), relaxed frequency-dependently in response to electrical stimulation. Maximum relaxation was obtained at 6-8 Hz, and amounted to 56 +/- 2%, 77 +/- 3% and 62 +/- 6% of the agonist-induced tension in preparations contracted by NA, carbachol, or ET-1, respectively. Exposure to NG-nitro-L-arginine (L-NOARG; 10(-7)-10(-5) M) concentration-dependently reduced the relaxant response in preparations contracted by NA. L-NOARG (10(-6) M) reduced the maximal response to 51 +/- 8% of control. L-NOARG (10(-5) M) abolished all relaxation, and unmasked a contractile component; D-NOARG had no effect. Also in trigonal preparations, where the tension had been raised by carbachol or ET-1, L-NOARG (10(-5) M) markedly reduced relaxations evoked by electrical stimulation. 3. In trigonal preparations contracted by NA, maximal relaxation was increased after pretreatment with L-ARG (10(-3) M), and the inhibitory effect of L-NOARG (10(-6) M) was prevented. Incubation of the trigonal strips with methylene blue had no effect on relaxations elicited at frequencies less than 6 Hz, but a small inhibition was observed at higher frequencies. 4. Administration of NO (present in acidified solution of NaNO2) induced concentration-dependent relaxations in trigonal preparations contracted by NA, carbachol, or ET-1.L-NOARG (10-5 M) and L-ARG (10-3M) had no effect on these relaxations. However, methylene blue (10-S M) significantly shifted the concentration-response curve for NO to the right. NANC-relaxation and NO-induced relaxation of trigonal preparations were both inhibited by oxyhaemoglobin (10-5 M) and pyrogallol (10-4 M).5. In urethral preparations precontracted by NA, electrical stimulation caused frequency-dependent relaxations. A maximum relaxation of 73 +/- 4% was obtained at 10 Hz. Also in the urethra, NANCrelaxation was blocked by L-NOARG (10-5 M), and a contractile response generally appeared.6. Detrusor strips treated with alpha-beta methylene ATP (10-i M) and atropine (10-6 M), and then contracted by ET-1, showed relaxations (19 +/- 3% of the induced tension) in response to electrical field stimulation (2-20 Hz) only when the tension was high. No response at all, or small contractions, were found in response to electrical stimulation in K+ (35 mM)-contracted detrusor strips. Detrusor preparations contracted by carbachol were concentration-dependently relaxed by exogenously administered NO, SIN-1 (NO-donor), and isoprenaline, whereas vasoactive intestinal polypeptide had minor effects. NO and SIN-1 induced maximal relaxations of 63 +/- 3% and 70 +/- 4%, respectively, of the tension induced by carbachol. Isoprenaline produced an almost complete relaxation (96 +/- 4%).7. The results suggest that NANC-nerve mediated relaxation, involving the L-ARG/NO pathway, can be demonstrated consistently in the pig trigonal and urethral, but not in detrusor smooth muscle. The importance of this pathway for lower urinary tract physiology and pathophysiology remains to be established.


Study of mechanisms of glucocorticoid hypertension in rats: endothelial related changes and their amelioration by dietary fish oils.

1. To investigate possible mechanisms of increased systolic blood pressure after 1 weeks treatment with dexamethasone and its amelioration by fish oil feeding, we have examined the reactivity of aortic rings and perfused mesenteric resistance vessels. 2. Thirty six Sprague-Dawley rats were initially divided into two groups and fed a semisynthetic diet containing either (10% by weight) hydrogenated coconut oil and safflower oil mixture (HCO/S) (24 rats) or fish oil (12 rats) for 5 weeks. From the end of the fourth week, dexamethasone (1.25 mg ml-1) in drinking water, was given to half the rats on hydrogenated coconut oil (HCO/S+Dex) and to the fish oil-fed group (fish oil+Dex). 3. One week of dexamethasone treatment raised systolic blood pressure in the HCO/S+Dex rats but not in the fish oil+Dex group. 4. Endothelium-dependent relaxation to acetylcholine (ACh) was decreased in aortic rings taken from HCO/S+Dex rats compared to rats on HCO/S alone. Relaxant responses to ACh of aortic rings from rats given fish oil+Dex were intermediate between the three groups. Aortic endothelium-independent responses to sodium nitroprusside (SNP) were unchanged between the groups, while aortic contractile responses to noradrenaline were similar in all the groups. 5. In the perfused mesenteric resistance artery, sensitivity to noradrenaline was decreased in rats given fish oil and dexamethasone compared to the other two groups. There were no differences in resistance vessel relaxation to ACh or SNP between groups. 6. Serum corticosterone levels, used as a marker of dexamethasone absorption, were substantially suppressed in dexamethasone-treated rats but levels were higher in rats on fish oil than on HCO/S diets. 7. We suggest that the glucocorticoid-induced rise in systolic blood pressure may be due in part to decreased aortic compliance as a consequence of impaired endothelium-dependent relaxation and perhaps reduced nitric oxide synthesis. Fish oil feeding may ameliorate this rise in blood pressure through (i) changes in dexamethasone absorption, (ii) decrease in reactivity to noradrenaline of perfused mesenteric resistance arteries, (iii) an increase in endothelium-dependent relaxation to ACh or a combination of these three factors.


Differences in evoked dopamine efflux in rat caudate putamen, nucleus accumbens and tuberculum olfactorium in the absence of uptake inhibition: influence of autoreceptors.

1. Dopamine efflux following single pulse or train of pulse stimulations was measured in slices of rat caudate putamen, nucleus accumbens and tuberculum olfactorium, using fast cyclic voltammetry at a carbon fibre microelectrode; 1, 5, 10, 20 or 50 pulses were applied at each location at frequencies varying from 10 Hz to 500 Hz. 2. There are significant differences in the ability of the different regions to increase dopamine efflux following single or repeated electrical stimulation. 3. Highest release in response to a single pulse is observed in the caudate putamen (approximately 250 nM dopamine), but the ratio of the peak dopamine overflow following a train of 20 pulses (50 Hz) when compared to a single pulse is rarely greater than three. 4. Release following single pulse stimulation in the nucleus accumbens (approximately 185 nM dopamine) is often slightly less than in the caudate putamen, but the ratio of peak release when trains of 20 pulses (50 Hz) are compared to single pulse stimulation has been as great as seven fold. 5. The tuberculum olfactorium releases the least dopamine of the three regions following a single pulse stimulation (approximately 40 nM dopamine), but the ratio of peak dopamine release following trains of 20 pulses (50 Hz) when compared to single pulse can result in a value approaching 20. 6. When 20 pulses are applied to the caudate putamen at frequencies ranging from 10 to 500 Hz, the peak efflux is essentially the same (frequency/release profile is flat), with the maximum increase only 140% that of a single pulse.7. By contrast, in the nucleus accumbens and the tuberculum olfactorium, well defined frequencyrelease relationships are seen following 20 pulses applied at 10, 20 and 50 Hz; at higher frequencies the dopamine release decreases as frequency is increased.8. Experiments with sulpiride or metoclopramide (dopamine D2 receptor antagonists) indicate that dopamine release in the caudate putamen is not regulated by dopamine autoreceptor activation by endogenous dopamine under our experimental conditions (in the absence of reuptake inhibtion). By contrast, in the nucleus accumbens and in the tuberculum olfactorium, we present evidence to show that at frequencies of stimulation up to 20 Hz, endogenous dopamine acts at dopamine autoreceptors to inhibit further release of dopamine but a minimum exposure time of between 500 and 1000 ms is needed for the response to D2 autoreceptor activation by endogenously released dopamine to be seen.


The role of induction of nitric oxide synthesis in the altered responses of jugular veins from endotoxaemic rabbits.

1. Endotoxaemia is characterized by hypotension, peripheral vasodilatation and a reduced response to vasoconstrictors. Clinical studies have indicated that venodilatation contributes to the haemodynamic changes, although there is no direct evidence for abnormal venous reactivity. In the present study, the role of nitric oxide (NO) in modifying the responses of rabbit isolated jugular veins was examined in vitro, 4 h after intravenous injection of endotoxin. 2. Treatment with endotoxin reduced the contractile response to the thromboxane-mimetic, 9,11-dideoxy-11 alpha, 9 alpha-epoxymethano-prostaglandin F2 alpha (U-46619). This affect was endothelium-independent. The response was partially restored by the NO synthase inhibitor. NG-monomethyl-L-arginine (L-NMMA 300 microM). 3. Jugular veins from control animals did not contract to L-NMMA whereas those from endotoxin-treated animals showed concentration-dependent contractions to L-NMMA. The contractions produced by L-NMMA were reversed by L-arginine but not by D-arginine. Treatment of the animals with dexamethasone (4 mg kg-1) 1 h prior to administration of endotoxin significantly attenuated the response to L-NMMA. 4. The response to sodium nitroprusside did not differ significantly between veins from control and endotoxin-treated animals. Endothelial denudation did not alter the sensitivity of the veins to sodium nitroprusside. Acetylcholine produced endothelium-dependent relaxations which were similar in veins from control and endotoxin-treated animals. 5. The results of this study demonstrate that intravenous administration of endotoxin induces hyporesponsiveness to U-46619 in jugular veins. This effect is mediated, at least in part, by the induction of NO synthesis in smooth muscle. The induction is prevented by prior treatment with dexamethasone.


Coeliac haemodynamic effects of endothelin-1, endothelin-3, proendothelin-1 [1-38] and proendothelin-3 [1-41] in conscious rats.

1. Conscious, chronically-instrumented, Long Evans rats were given bolus doses of endothelin-1, endothelin-3 (both at 0.01 and 0.1 nmol kg-1), proendothelin-1 [1-38] and proendothelin-3 [1-41] (both 0.1 and 1 nmol kg-1) in order to compare their effects on coeliac haemodynamics, because it has been reported that, in conscious dogs, endothelin-1 has paradoxical, prolonged hyperaemic vasodilator effects in this vascular bed. Measurements were made also of mesenteric and hindquarters haemodynamics for comparison. In a separate experiment, endothelin-1 (0.1 nmol kg-1) was given before and 20 min after the onset of an infusion of mecamylamine (50 mumol kg h-1) to ensure that the responses measured were not confounded by rapid reflex changes in autonomic activity. 2. None of the peptides caused any increases in coeliac flow or any sustained rises in coeliac vascular conductance, although such changes were clear-cut in the hindquarters vascular bed following the higher dose of endothelin-1 and endothelin-3. In animals treated with mecamylamine the regional haemodynamic effects of the higher dose endothelin-1 were not different from those in animals with intact baroreflexes. 3. Although the lower dose of both endothelin-1 and endothelin-3 caused less marked coeliac, than mesenteric vasoconstriction, this difference was not apparent with the higher dose of the peptides, or with proendothelin-1 [1-38]. However, proendothelin-3 [1-41] had less marked coeliac and hindquarters vasoconstrictor effects than proendothelin-1 [1-38], in spite of both peptides causing similar changes in mesenteric haemodynamics.These differences could have been due to regional differences in the conversion of proendothelin-l [1-38] and proendothelin-3 [1-41] to endothelin-l and endothelin-3,respectively. Our findings contradict the proposition that exogenous proendothelin-3[1-41] is not converted into endothelin-3 in vivo.4. Since, in contrast to endothelin-1 and endothelin-3, proendothelin-1 [1-38] and proendothelin-3 [1-41] caused only small hindquarters vasodilatations, but large vasoconstrictions, it is feasible that the vasodilator responses to exogenous endothelin-l and endothelin-3 are pharmacological phenomena, and that, in vivo, the production of endothelins from proendothelins exerts widespread vasoconstrictor effects.


Effect of lignocaine on arginine-vasopressin plasma levels: baseline or induced by frusemide.

1. To assess whether or not lignocaine influences baseline and frusemide-induced (5 mg kg-1) plasma concentrations of arginine-vasopressin (AVP), 2 groups of rabbits received an infusion of lignocaine (130 micrograms min-1 kg-1) for 6 h. Lignocaine-induced changes in AVP plasma concentrations were substantiated by measurement of diuresis and natriuresis and hepatic plasma flow, by means of an infusion of indocyanine green (ICG) (249 micrograms min-1 kg-1). 2. Baseline plasma AVP levels were 4.9 +/- 0.9 pg ml-1 (+/- s.e.), and following lignocaine, these values were reduced to 0.7 +/- 0.1 pg ml-1 (P less than 0.01). Frusemide increased AVP levels to 134.1 +/- 73.6 pg ml-1 (P less than 0.05) and lignocaine totally prevented this increase, e.g. mean AVP levels of 2.7 pg ml-1. 3. Lignocaine enhanced baseline diuresis secondary to an increase in free water clearance; none of the experimental conditions affected the diuresis and natriuresis induced by frusemide. 4. Frusemide reduced the hepatic plasma flow and this decrease was not reversed by the infusion of lignocaine. 5. It is concluded that in healthy rabbits lignocaine reduces baseline secretion of AVP and its antidiuretic effect; in addition, lignocaine prevents the rise in AVP induced by frusemide.


Synergistic anti-nociceptive effect of L-NG-nitro arginine methyl ester (L-NAME) and flurbiprofen in the mouse.

1. L-NG-nitro arginine methyl ester (L-NAME) administered i.p. produces anti-nociception in the mouse assessed by the formalin-induced paw licking and acetic acid-induced abdominal constriction models. The non-steroidal anti-inflammatory drug (NSAID), flurbiprofen, was similarly anti-nociceptive in both models. 2. Combination of a sub-threshold dose of L-NAME (10 mg kg-1) with increasing doses of flurbiprofen (25- 75 mg kg-1) or a sub-threshold dose of flurbiprofen (50 mg kg-1) with increasing doses of L-NAME (10- 100 mg kg-1) resulted in potentiated anti-nociception in the formalin model. Combined therapy with sub-threshold doses of L-NAME (10 mg kg-1) and indomethacin (10 mg kg-1) also resulted in significant anti-nociception. In addition, combining sub-threshold doses of L-NAME (12.5 mg kg-1) and flurbiprofen (2 mg kg-1) significantly reduced acetic acid-induced abdominal constriction. 3. L-NAME (10 mg kg-1) administered i.p. caused a significant (approximately 35%) increase in MAP in the urethane-anaesthetized mouse. Flurbiprofen (50 mg kg-1) was inactive. Combination treatment with L-NAME (10 mg kg-1) and flurbiprofen (50 mg kg-1) failed to elevate MAP above that observed with L-NAME alone. Neither L-NAME (10 mg kg-1) nor flurbiprofen (50 mg kg-1) either alone or in combination significantly altered mouse locomotor activity. 4. These results suggest that L-NAME and flurbiprofen/indomethacin act synergistically in their anti-nociceptive action in the mouse. Combination therapy with L-NAME and flurbiprofen and a similar NSAID may provide an alternative to the clinical control of pain in man.


Pituitary adenylate cyclase activating polypeptides, PACAP-27 and PACAP-38: stimulators of electrogenic ion secretion in the rat small intestine.

1. The effects of pituitary adenylate cyclase activating polypeptide (PACAP)-27 and PACAP-38 were investigated and compared with vasoactive intestinal polypeptide (VIP) responses in voltage clamped preparations of rat jejunum. Under these conditions electrogenic ion secretion was continuously recorded. 2. PACAP-27 is the most potent secretagogue described thus far, exhibiting a concentration-dependent dual secretory action. At low concentrations it stimulated rapid, transient secretory responses (not seen with either PACAP-38 or VIP) and these were inhibited by tetrodotoxin (TTX). At higher nM concentrations of PACAP-27 more prolonged secretory responses predominated which were insensitive to TTX. 3. In the presence of TTX, the concentration-response curve to PACAP-27 gave an EC50 value of 29.4 +/- 5.4 nM (n = 4) compared with 0.8 +/- 0.1 nM (n = 9) for PACAP-27 alone and 30.6 +/- 5.6 nM (n = 5) for PACAP-38. C-terminal fragments of PACAP-38 were not significantly effective. 4. Blockade of muscarinic and nicotinic receptors partially inhibited the low concentration effects of PACAP-27. Substance P desensitization and capsaicin pretreatment were effective at inhibiting the transient secretory PACAP-27 responses. Evidence is presented for selective, high affinity PACAP-27 receptors on submucous neurones innervating the mucosal region of the rat jejunum.


Human bronchial cyclic nucleotide phosphodiesterase isoenzymes: biochemical and pharmacological analysis using selective inhibitors.

1 The aims of the present study were to characterize the cyclic nucleotide phosphodiesterase (PDE) isoenzyme activities present in human bronchi and to examine the ability of selective isoenzyme inhibitors to relax histamine and methacholine precontracted preparations of human bronchi. 2 Three separations of pooled human bronchial tissue samples were performed. Ion-exchange chromatography showed that the soluble fraction of human bronchial preparations contains PDE I, II, III, IV and V isoenzyme activities. Multiple forms of PDE I and PDE IV were observed and PDE IV was the main cyclic AMP hydrolytic activity. 3 3-Isobutyl-l-methylxanthine (IBMX) non-selectively inhibited all separated isoenzyme activities. Zaprinast selectively inhibited PDE V, but also effectively inhibited one of the two PDE I isoforms identified. The PDE IV selective inhibitors rolipram and RO-201724, inhibited the PDE IV activities as did the dual PDE III/IV inhibitor, Org 30029. Org 9935, a PDE III selective inhibitor, potently attenuated part of the PDE IV activity peak in one of three separations performed, indicating that some PDE III activity may co-elute with PDE IV under the experimental conditions employed. 4 PDE IV-selective (rolipram), PDE III-selective (Org 9935) and dual PDE III/IV (Org 30029) inhibitors were effective relaxants of human bronchial smooth muscle. The PDE V/PDE I inhibitor, zaprinast was relatively ineffective. 5 The present study demonstrates in human bronchi, as in animal airways smooth muscle, that inhibitors of PDE III, PDEIV and dual PDE III/IV have potentially useful bronchodilator activity and are worthy of further consideration as anti-asthma drugs.


Altered microvascular reactivity to endothelin-1, endothelin-3 and NG-nitro-L-arginine methyl ester in streptozotocin-induced diabetes mellitus.

1 We have determined the dermal microvascular effects of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 100 nmol/site), endothelin-1 (ET-1, 0.1-10 pmol/site) and ET-3 (0.1-30 pmol/site) in rats with streptozotocin (STZ)-induced diabetes mellitus. Cutaneous blood flow changes as measured by a 133xenon (133Xe) clearance technique, were determined in diabetic rats four weeks after treatment with streptozotocin (STZ) and compared with responses measured in normal rats four weeks after treatment with saline. 2 Resting skin blood flow was similar in diabetic and in normal rats, as measured by 133Xe clearance and laser Doppler flowmetry. 3 Intradermal NG-nitro-L-arginine methyl ester (L-NAME) reduced skin blood flow in normal rats by 55.2 +/- 2.6% as measured by 133Xe clearance, (n = 9). L-NAME was significantly less effective in diabetic rats, inducing a 40.9 +/- 7.7% decrease in blood flow (n = 9, P less than 0.05). The enantiomer D-NAME had no effect in either group of rats. 4 Low doses of ET-1 and ET-3 injected intradermally induced dose-dependent decreases in blood flow, measured by 133Xe clearance, which were similar in both groups of rats. However, the responses to the highest doses of ET-1 (10 pmol/site) and ET-3 (10 and 30 pmol/site) were significantly reduced in the diabetic compared with the normal rats (P less than 0.05).In addition vasoconstriction to the highest doses of vasopressin (0.3 and 3 pmol/site) and vasodilatation to the neuropeptide calcitonin gene-related peptide (CGRP, 1O pmol/site) were similarly reduced in the diabetic rats (P <0.05).5. The decrease in blood flow induced by submaximal doses of ET-1 was enhanced by co-injection with L-NAME (100 nmol/site) in both diabetic and normal rats. However, this enhanced response was significantly reduced in the diabetic rats (P<0.05). A similar pattern of responses were observed to ET-3 in the presence and absence of L-NAME.6. These results indicate that the cutaneous microvasculature of rats with STZ-induced diabetes responds differently to intradermal ET-1 and ET-3 compared with normal rats; a similarly altered vascular reactivity was observed with vasopressin and CGRP. Hence, the diabetic microcirculation has impaired responses to several vasoconstrictors and a vasodilator. The effect of the nitric oxide synthase inhibitor L-NAME is also suppressed in the diabetics, suggesting that there may be decreased local production of, or response, to nitric oxide.


Pharmacological evidence for distinct endothelin receptors in guinea-pig bronchus and aorta.

The ETA receptor antagonist, BQ-123 (1 microM) potently antagonized endothelin-1 (ET-1) concentration-response curves in guinea-pig aorta (pKB = 7.1). However, 10 microM BQ-123 was without effect on ET-1-induced contractions in guinea-pig bronchus. The ETB-selective agonist, sarafotoxin S6c did not contract the aorta but was a potent and effective contractile agonist in the bronchus. BQ-123 (10 microM) was without effect on sarafotoxin S6c-induced contractions in the bronchus. These data provide evidence for distinct endothelin receptors in guinea-pig aorta and bronchus, which appear to be predominantly of the ETA and non-ETA, perhaps ETB, subtypes, respectively.


The mechanism by which procaine inhibits catecholamine secretion from bovine chromaffin cells.

1. We have investigated the action of procaine on stimulus-secretion coupling in bovine adrenal chromaffin cells. 2. Procaine inhibited the catecholamine secretion evoked by 500 microM carbachol (CCh) with an IC50 of 35 microM and the associated calcium influx (IC50 60 microM). It inhibited the catecholamine secretion evoked by depolarization with high potassium by less than 20% even at the highest concentrations tested (3.2 mM). 3. The secretion evoked by CCh was associated with an increase in sodium influx. This evoked influx was also inhibited by procaine (IC50 80 microM). 4. This selective action of procaine on the CCh-evoked catecholamine secretion was investigated further by patch-clamp techniques. 5. In agreement with the ion flux studies, procaine inhibited the inward current evoked by CCh. Procaine also altered the spectral characteristics of the noise associated with the agonist-induced current by adding an additional high frequency component. The amplitude of this component showed an e-fold increase for a 55 mV membrane hyperpolarization. 6. Data from cell-attached patches showed that increasing concentrations of procaine produced a progressive fall in the mean channel open time and an increase in mean blocked time. This combination led to a decrease in mean burst length. In addition, Popen was reduced by 50 microM procaine. These changes in channel conducting time were sufficient to account for the reduction in inward current. A limited study of the action of procaine on nicotinic channels in outside-out patches gave similar results. 7. The data were considered in relation to various schemes of anaesthetic-channel interactions. The data did not fit the sequential blocking model or the extended channel block model but could be fitted to a modified sequential blocking model in which the rate constant for channel reopening after block was itself subject to modulation by the anaesthetic and the blocked channel could close without passing through the open state.


Tracheal relaxation induced by potassium channel opening drugs: its antagonism by adrenergic neurone blocking agents.

1. We have studied the ability of some adrenergic neurone blocking agents to inhibit the tracheal relaxant actions of isoprenaline, theophylline and the potassium channel openers (KCOs) BRL 38227, pinacidil and RP 52891. 2. BRL 38227, isoprenaline, pinacidil, RP 52891 and theophylline each caused concentration-dependent suppression of the spontaneous tone of guinea-pig isolated trachealis. The maximal relaxant effects of isoprenaline and pinacidil were equal to that of theophylline. In contrast, the maximal effects of BRL 38227 and RP 52891 were approximately 85-95% of that of theophylline. 3. Guanethidine (5-500 microM) did not itself modify the spontaneous tone of the trachealis muscle but antagonized BRL 38227 in a concentration-dependent manner. Guanethidine (50 microM) also antagonized pinacidil and RP 52891. However, guanethidine did not antagonize either isoprenaline or theophylline. 4. Bretylium (50 microM) did not itself modify the spontaneous tone of the trachealis muscle but antagonized BRL 38227, pinacidil and RP 52891. Bretylium did not antagonize either isoprenaline or theophylline. 5. Guanidine (50 and 500 microM) did not itself modify the spontaneous tone of the trachea and failed to modify the tracheal relaxant activity both of BRL 38227 and theophylline. 6. BRL 38227 (1 and 10 microM) stimulated, in a concentration-dependent manner, the efflux of 86Rb+ from strips of bovine trachealis muscle that had been pre-loaded with the radiotracer. Guanethidine (50 microM), bretylium (50 microM) and debrisoquine (50 microM) did not themselves modify the efflux of 86Rb+ from bovine trachealis but each of these agents markedly inhibited the stimulant effect of BRL 38227 (10 microM) on 86Rb+ efflux.7. It is concluded that the adrenergic neurone blocking agents guanethidine and bretylium can inhibit the tracheal relaxant actions of KCOs such as BRL 38227, pinacidil and RP 52891 without antagonizing isoprenaline or theophylline. The ability of the adrenergic neurone blocking agents to antagonize BRL 38227 in promoting 86Rb+ efflux from trachealis muscle may suggest that the adrenergic neurone blocking agents act to prevent the opening of the plasmalemmal K+-channel that is involved in the tracheal relaxant actions of the KCOs.


The contribution of charge to affinity at functional (M3) muscarinic receptors in guinea-pig ileum assessed from the effects of the carbon analogue of 4-DAMP methiodide.

1. 4-Diphenylacetoxy-1:1-dimethyl cyclohexane (carbo-4-DAMP) is the carbon analogue of 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) methiodide. The compounds differ only in that the quaternary nitrogen atom in 4-DAMP methiodide is replaced by a quaternary carbon atom, which is uncharged. 2. Carbo-4-DAMP appears to act competitively at functional (M3) muscarinic receptors in guinea-pig ileum. Estimates of log affinity constant are 6.0 at 30 degrees C and 5.9 at 37 degrees C, i.e. the compound has 0.1% of the affinity of 4-DAMP methobromide. 3. The absence of charge makes little difference to the conformation as determined by X-ray crystallography. The bond lengths and angles are very similar, though the bonds in the cyclohexane ring of carbo-4-DAMP are consistently slightly longer than those in the piperidinium ring of 4-DAMP methiodide, and the presence of the charge slightly reduces the space between molecules. 4. The difference between the affinities of 4-DAMP methobromide and carbo-4-DAMP indicates that the contribution of coulombic forces to the binding between 4-DAMP methiodide and muscarinic (M3) receptors is at least 17 kJ mol-1 (4.1 kcal mol-1) at 37 degrees C. How much this is an underestimate depends upon how much hydrophobic binding is greater with the uncharged compound.


Ca(2+)-stores mobilization by diadenosine tetraphosphate, Ap4A, through a putative P2Y purinoceptor in adrenal chromaffin cells.

1. Diadenosine tetraphosphate (Ap4A) evoked a concentration-dependent increase in cytosolic [Ca2+] in resting chromaffin cells. The EC50 value for this action was 28.2 +/- 6.6 microM. This effect was also produced by diadenosine pentaphosphate (Ap5A) with an EC50 of 50 +/- 7 microM. 2. In contrast with this effect, pretreatment with Ap4A or Ap5A induced a 30% reduction in Ca2+ entry following 10 microM dimethylphenylpiperazinium. 3. The elevation in cytosolic [Ca2+] induced by Ap4A was persistent in approximately 100 nM external [Ca2+] and was sensitive to depletion of internal Ca2+ stores by a bradykinin prepulse or whole cell depletion in Ca2+. 4. The effect of Ap4A was mimicked and desensitized by the agonist adenosine 5'-O-(2-thiodiphosphate), and blocked by the P2Y-receptor antagonist, cibachrome blue. The P2X-receptor agonist alpha,beta-methylene adenosine 5'-triphosphate was inactive both by itself or in combination with Ap4A. This is compatible with a P2Y-purinoceptor-mediated action.


Modulation by opioids and by afferent sensory neurones of prostanoid protection of the rat gastric mucosa.

1. Pretreatment with capsaicin, to deplete sensory neuropeptides from primary afferent neurones or the administration of morphine (9 mg kg-1, i.v.), which can inhibit neuropeptide release, augmented gastric mucosal injury induced by a 5 min challenge with intragastric ethanol in the rat, as assessed by macroscopic and histological evaluation. 2. Morphine administration substantially attenuated the protective actions of the prostaglandin analogue 16,16 dimethyl prostaglandin E2 (dm PGE2; 0.5-20 micrograms kg-1, p.o.) against ethanol-induced damage. This reduced degree of protection by dmPGE2 was not however, the consequence of the enhanced level of damage. 3. These actions of morphine in reducing prostaglandin protection against mucosal injury were abolished by pretreatment (5 min) with naloxone (1 mg kg-1, i.v.) or the peripherally acting opioid antagonist, N-methyl nalorphine (6 mg kg-1, i.v.). 4. Capsaicin pretreatment (2 weeks before study), likewise attenuated the protective actions of dmPGE2, although to a lesser degree than did morphine. 5. These findings, thus implicate the involvement of capsaicin- and opioid-sensitive afferent neurones in the processes by which exogenous prostanoids can protect the gastric mucosa from damage.


The nucleotide receptors on mouse C2C12 myotubes.

1. The response of C2C12 mouse myotubes to stimulation with adenosine triphosphate (ATP) and other nucleotides was studied by measuring changes in membrane potential. 2. A transient hyperpolarization followed by a slowly declining depolarization of the cells was observed in the presence of ATP (10 microM-1 mM). 3. The hyperpolarization was not observed in the absence of external calcium, and was abolished in the presence of tetraethylammonium (20 mM) or the bee toxin, apamin (0.1 microM). The depolarization was reduced under low sodium conditions. 4. A biphasic change in membrane potential was also recorded in the presence of adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S) and the pyrimidine uridine triphosphate (UTP), while the ATP derivatives and analogues, adenosine diphosphate, adenosine, alpha,beta-methylene ATP and 2-methylthio ATP and the nucleotides, guanosine triphosphate and cytidine triphosphate, did not affect the membrane potential of the myotubes. 5. The hyperpolarization elicited by ATP gamma S or UTP was also blocked by apamin and abolished under Ca(2+)-free conditions. 6. In contrast to ATP and ATP gamma S, the depolarization evoked by UTP was unaffected under low Na+ and less sensitive to the antagonistic action of suramin. 7. The ATP and UTP responses at maximal concentration were not additive after simultaneous application. ATP elicited a depolarization if applied after UTP, while UTP did not change membrane potential following the application of ATP. 8. The concentration-response curves of the effective nucleotides were shifted to the right in the presence of suramin, suggesting competitive antagonism.9. These results can be explained by the presence of 'nucleotide receptors' mediating the ATP/UTPinduced hyperpolarization and depolarization in C2C12 myotubes. Furthermore, an increase in Na+-conductivity can be exclusively activated by ATP.


Noradrenaline-stimulated inositol phosphate accumulation in arteries from spontaneously-hypertensive rats.

1. The effects of noradrenaline upon polyphosphoinositide (PPI) breakdown was investigated by measuring the accumulation of inositol phosphates (IPs) in tail arteries from normo- (WKY) and spontaneously-hypertensive (SHR) rats. 2. Noradrenaline (10(-7)-10(-3) M) evoked a concentration-dependent increase in total IP accumulation in both WKY and SHR rats but no significant differences between the populations were detected. 3. In contrast, significant differences in the accumulation of the individual IPs, which contributed to the total IP, occurred. A significantly greater noradrenaline-stimulated accumulation of inositol trisphosphate (IP3) was observed in tissues from SHR compared with those from WKY rats at each effective concentration of noradrenaline. This was paralleled by an equivalent reduction in inositol monophosphate (IP1) accumulation, consistent with the lack of a significant difference in noradrenaline-stimulated total IP accumulation between the two populations. 4. In time course studies, an enhanced noradrenaline-induced accumulation of IP3, in SHR compared to WKY rats, occurred from the earliest time point studied after the addition of the catecholamine both in the presence and absence of LiCL (10 mM). In the presence of LiCl (10 mM) no significant difference in noradrenaline-evoked total IP accumulation between SHR and WKY rats was observed; in the absence of LiCl noradrenaline-evoked a greater total IP accumulation in SHR than in WKY rats at all time points investigated. 5. These studies suggest that the main reason for the enhanced noradrenaline-induced accumulation of IP3 in arteries from SHR rats is a reduced rate of dephosphorylation of both IP3 and inositol bisphosphate (IP2) rather than a greater formation of IP3 from PPIs.6. This enhanced accumulation of IP3 may result in an increased calcium mobilisation accounting for the increased contractility to noradrenaline of tail arteries from SHR as compared with those from WKY rats.


Investigation of the 5-hydroxytryptamine receptor mediating the 'maintained' short-circuit current response in guinea-pig ileal mucosa.

1. 5-Hydroxytryptamine (5-HT) stimulated a biphasic increase in short-circuit current (SCC) in guinea-pig isolated ileal mucosa. The initial 'spike' response to 5-HT was inhibited by tetrodotoxin (0.3 microM). We have investigated the 5-HT receptor mechanism(s) controlling the second 'maintained' component of the response which remained after treatment with tetrodotoxin. 2. 5-HT stimulated concentration-related increases in SCC with an EC50 value of 5.4 microM. Isobutyl-methylxanthine (IBMX, 10 microM) produced a six fold leftward shift of this concentration-response curve, suggesting the involvement of a cyclic nucleotide(s) in these responses. 3. In the presence of IBMX, 5-HT stimulated reproducible increases in SCC with an EC50 value of 0.9 microM. The rank order of potency of indole agonists in these tests was 5-HT greater than or equal to 5-methoxytryptamine greater than 5-carboxamidotryptamine = alpha-methyl-5-HT much greater than 2-methyl-5-HT. 4. The substituted benzamides were partial agonists. Metoclopramide and cisapride produced approximately 20% of the 5-HT maximum, and renzapride and R,S-zacopride produced approximately 50% of the 5-HT maximum. Metoclopramide and cisapride inhibited the SCC responses to 5-HT with apparent pKB values of 4.8 and 7.0 respectively. 5. The SCC responses to 5-HT were not inhibited by antagonists selective for 5-HT1 (methysergide, methiothepin), 5-HT2 (ketanserin) or 5-HT3 (ondansetron, ICS205-930) receptors. 6. The SCC responses to 5-methoxytryptamine, 5-carboxamidotryptamine, alpha-methyl-5-HT and R,S-zacopride, but not 5-HT, were selectively inhibited by high concentrations of ICS205-930 with apparent pKB values of approximately 6.7. A possible interpretation of these results is that the 'maintained' SCC response to 5-HT is mediated by a heterogeneous population of 5-HT receptors. One of these receptors exhibits the characteristics of the putative 5-HT4 receptor.


Contractile activity of big endothelin-1 on the human isolated bronchus.

1. We have studied the contractile activity of the 39 amino acid precursor of endothelin-1 (ET-1), big endothelin-1 (big ET-1), on human isolated bronchi. The contribution of the metalloproteases, neutral endopeptidase (NEP) and angiotensin converting enzyme (ACE), in the presence or absence of the epithelium lining, by use of specific inhibitors, was also evaluated on the effects of big ET-1. 2. Big ET-1 elicited a potent contraction of human isolated bronchus. The -log EC50 value for big ET-1 was 7.53 +/- 0.08 (n = 11) and Emax 78.5 +/- 3.8% (% of ACh 3mM). 3. Incubation of human isolated bronchi with the NEP inhibitor phosphoramidon (10(-5) M) induced a rightward shift of the concentration-response curve induced by big ET-1 (10(-9) M to 3 x 10(-7) M). Similar results were observed when human bronchi were incubated with thiorphan (10(-5) M), but the shift to the right was significantly less (P less than 0.01) than that observed in the case of phosphoramidon (-0.35 +/- 0.05 vs -0.67 +/- 0.07 log unit). 4. The two inhibitors of angiotensin I converting enzyme (ACE), captopril or enalapril diacid, did not affect the concentration-response curve for contraction induced by big ET-1. 5. When the epithelium was removed, a leftward shift of the concentration-response curve of big ET-1 (10(-9) M to 3 x 10(-7) M) was observed. Incubation of human isolated bronchi with phosphoramidon or thiorphan (10-5M) or with enalapril diacid or captopril did not modify the leftward shift of the concentration-response curve for big ET-1 after epithelium removal.6. These results suggest that big ET-1 elicits potent contractile activity in the human isolated bronchus and that its effect is the consequence of the conversion to ET-1 by a phosphoramidon-sensitive metalloprotease which, although different from NEP and ACE, appears to be similar to the endothelinconverting enzyme (ECE) described in other studies in animals.


Actions of 5-hydroxytryptamine and 5-HT1A receptor ligands on rat dorso-lateral septal neurones in vitro.

1. The actions of 5-hydroxytryptamine (5-HT) and some 5-HT1A receptor ligands on neurones in the rat dorso-lateral septal nucleus were recorded in vitro by intracellular recording techniques. 2. In the presence of tetrodotoxin (1 microM) to block any indirect effects, bath application of 5-HT (0.3-30 microM) hyperpolarized the neurones in a concentration-dependent manner and reduced membrane resistance. The hyperpolarization did not exhibit desensitization and was sometimes followed by a small depolarization. 3. The 5-HT1A receptor ligands, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), N,N-dipropyl-5-carboxamidotryptamine (DP-5-CT) and buspirone but not the non-selective 5-HT1 receptor agonist, 1-m-trifluoromethylphenylpiperazine (TFMPP), also hyperpolarized the neurones. 4. 5-HT, 8-OH-DPAT and DP-5-CT appeared to act as full agonists whereas buspirone behaved as a partial agonist. The estimated EC50S were: DP-5-CT 15 nM, 8-OH-DPAT 110 nM, 5-HT 3 microM and buspirone 110 nM. 5. At a concentration of 3 microM, the putative 5-HT1A receptor antagonists, spiperone, methiothepin, NAN-190 (1-(2-methoxyphenyl)-4-[4-(2-pthalimido)butyl]piperazine) and MDL 73005EF (8-[2-(2,3-dihydro-1,4-benzodioxin-2-yl-methylamino)ethyl]-8- azaspiro[4,5]decane-7,9-dione methyl sulphonate), produced a parallel rightward shift in the concentration-response curve to 5-HT with no significant reduction in the maximum response. The estimated pA2 values were: NAN-190 6.79, MDL 73005EF 6.59, spiperone 6.54 and methiothepin 6.17.6. The 5-HT2/5-HTlc receptor antagonist, ketanserin (3 microM) and the 5HT3 receptor antagonist, tropisetron (3 microM) did not antagonize the 5-HT-induced hyperpolarizations; however, ketanserin blocked the depolarization which sometimes followed the hyperpolarization.7. It is concluded that the 5-HT-induced membrane hyperpolarization of rat dorso-lateral septal neurones is mediated by 5-HTA receptors.


Potentiation of ADP-induced aggregation in human platelet-rich plasma by 5-hydroxytryptamine and adrenaline.

1. We have used dose-response curves to quantitate the potentiation of adenosine 5'-diphosphate (ADP)-induced aggregation and thromboxane (TXA2) generation by 5-hydroxytryptamine (5-HT) and adrenaline in human citrated platelet-rich plasma. We have also quantitated the inhibition of these responses by aspirin, ketanserin and yohimbine, singly and in pairs. 2. Ketanserin (5 microM) inhibited TXA2 production and the second wave of platelet aggregation induced by a range of concentrations of ADP alone. This indicates that endogenous 5-HT, released from the platelet dense granules, contributes significantly to responses induced by ADP. 3. When 5-HT (10 microM) was added before ADP, a lower concentration of ADP was required to cause 50% aggregation and TXA2 generation. The ratio of ADP concentrations (CR) to cause 50% aggregation in the presence and absence of 5-HT was 2.1 when only added 5-HT was considered, and 5.0 when endogenous 5-HT was also taken into account. 4. Potentiation of ADP-induced aggregation by 5-HT also occurred in the presence of aspirin, resulting in a CR of 2.3. As expected, ketanserin inhibited potentiation by 5-HT in the presence and absence of aspirin. Although aspirin caused substantial inhibition of aggregation induced by ADP and 5-HT (CR 3.4), further inhibition occurred when ketanserin was also present (CR 6.5). 5. A subthreshold concentration of adrenaline (0.25 microM) caused substantial potentiation of ADP-induced aggregation in the absence (CR 4.0) and presence (CR 2.0) of aspirin. As expected, yohimbine (9 microM) inhibited this potentiation.Maximum TXA2 generation induced by ADP increased from 32.5 to 59.4 pg per 106 platelets when adrenaline was present. Aggregation induced by ADP and adrenaline was markedly inhibited by aspirin (CR 5.1) but was further inhibited when yohimbine (9 microM) was also present (CR 10.0).6. Results from this in vitro study show ketanserin and yohimbine have the potential to be used in combination with aspirin as antithrombotic agents in vivo.


Effects of K+ channel blockers on the action potential of hypoxic rabbit myocardium.

1. In order to assess the role of different ionic currents in hypoxia-induced action potential shortening, we investigated the effects of blockers of voltage-dependent and ATP-sensitive K(+)-channel on the membrane potential of hypoxic rabbit hearts and papillary muscles. The response to blocking of the inward rectifier was studied at three external K+ concentration: 2.5, 5, and 7.5 mM. 2. Hypoxia produced a progressive decline in action potential duration (APD) that levelled off after 15 to 20 min. Steady state APD values at 25% and 95% repolarization (APD25 and APD95) were 26.0 +/- 1.9% and 42.2 +/- 2.4% of controls respectively. 3. Tetraethylammonium (TEA, 10 mM) delayed but did not reduce APD shortening at the steady state. 4. Blocking of IK1 with a mixture of 0.2 mM Ba2+ and 4 mM Cs+ lengthened APD in normoxia and prevented APD95 shortening in hypoxia. The APD25 shortening was significantly attenuated at all [K]o. 5. Glibenclamide (Glib, 30 microM) did not prevent APD shortening, but produced a progressive action potential (AP) lengthening after 15 min of hypoxia. Steady levels of 48 +/- 3.5% and 62 +/- 5.0% of controls for APD25 and APD95 respectively were reached after 45 min. 6. The relation between APD25 and pacing rate was determined in normoxic and hypoxic papillary muscles and the effects of 2 mM 4-aminopyridine (4-AP) were examined. Hypoxia attenuated the APD25 shortening currently observed when the stimulation rate was lowered from 1 to 0.1 Hz without altering the plateau reduction occurring at frequencies above 2 Hz. These effects were potentiated by 4-AP.7. Our data suggest that the accelerated AP repolarization in hypoxic rabbit myocardium represents a delicate balance of several outward currents: IKI, IK-ATP. and at least one yet unidentified current component rather insensitive to changes in [K]o and to K+ channel blockers.


The influence of endothelin-1 on human foeto-placental blood vessels: a comparison with 5-hydroxytryptamine.

1. The vasoconstrictor effect of endothelin-1 (3 x 10(-11) M-10(-7) M) was studied in successive generations of blood vessels of the foeto-placental vascular tree. These were the human umbilical arteries and veins, primary surface chorionic plate arteries, secondary chorionic plate arteries, tertiary surface chorionic plate arteries and veins and the secondary stem villus arterioles. The responses to endothelin-1 were compared with those to 5-hydroxytryptamine (10(-9) M-10(-5) M). Arterial preparations were gassed with 2.5% O2, 8% CO2 balance N2 and venous preparations were gassed with 5% O2, 6% CO2 balance N2 to simulate the conditions prevalent in utero. The influence of increasing the oxygen tension to 16% (that prevalent at birth) on the response to endothelin-1 on the umbilical arteries was also investigated. 2. All the arterial vessels tested were some ten times more sensitive to endothelin-1 than to 5-hydroxytryptamine and the venous preparations were ten times more sensitive to endothelin-1 than were their equivalent arteries. Increasing oxygen tension did not affect the responses to endothelin-1 in the umbilical artery. 3. Whilst the amplitude of the endothelin-1-induced response was uniform throughout the foetoplacental vascular tree, including the stem villus arterioles, the maximum response to 5-hydroxytryptamine decrease with successive generations and it had no significant effect on the stem villus arterioles.The ratios of the responses to 10- M endothelin-1: 10-7M 5-hydroxytryptamine in human umbilical arteries, primary surface chorionic plate arteries, secondary chorionic plate arteries,tertiary surface chorionic plate arteries and the secondary stem villus arterioles in the vessels (listed in order of decreasing vessel size) were 1:1.2, 1:0.36, 1:0.33, 1:0.35 and 1:0.04 respectively.4. In conclusion, endothelin-1 is a powerful vasoconstrictor at all levels of the foeto-placental vascular system including the stem villus resistance vessels. It may play an important role in maintaining foeto-plancental vascular resistance at the low oxygen tension which exists in this vascular system in utero.