THE EPINEPHRINE-BLOOD PLATELET CONNECTION WITH SPECIAL REFERENCE TO ESSENTIAL-HYPERTENSION

About three decades ago it was shown by an aggregometer that epinephrine activated blood platelets, and it was proposed that platelets could be the link between stress and cardiovascular disease. During the past 10 years this hypothesis has been tested in clinical studies. It has been found that subjects with hypertension consistently have raised plasma catecholamine levels and in particular elevated epinephrine levels. Arterial but not venous epinephrine concentrations correlated with plasma concentrations of the platelet-release reaction marker beta-thromboglobulin (BTG). Plasma BTG is elevated in hypertensive patients, and psychological stress (i.e., hypertension labeling) stimulates plasma epinephrine and BTG. When a physiologic dose of epinephrine is infused into essential hypertensive patients, platelet counts, platelet size, and plasma BTG concentrations increase more than in normotensive subjects. Data suggest that there is a connection between psychological stress, plasma epinephrine levels, and platelet function, especially in patients with essential hypertension.