Plasma catecholamines and production of thromboxane B2 by platelets after psychological and physical tests in normotensive and mild hypertensive subjects.
In our previous studies strenuous exercise, adrenaline infusion and surgical stress have been shown to evoke increased plasma thromboxane B2 (TxB2) concentrations and production by platelets. Here we report the effects of acute psychological and physical tests, during 24 h direct monitoring of blood pressure and heart rate, on plasma catecholamine levels and TxB2 production by platelets in normotensive, borderline and mild hypertensive subjects. After psychological tests plasma noradrenaline and adrenaline values in the whole material were slightly elevated as compared to the basal levels measured 24 h after the attachment of the cannula. TxB2 production remained unaltered. After physical tests both plasma noradrenaline and adrenaline were clearly increased as was also the TxB2 production by platelets. When the subjects were divided into normotensive and hypertensive ones, unexpectedly, basal plasma values of catecholamines were higher in normotensive volunteers but TxB2 production was more marked in hypertensive subjects.