Effects of prazosin on platelet aggregation and plasma beta-thromboglobulin in essential hypertension.

Platelet aggregation in response to adenosine 5'-diphosphate (ADP) and plasma levels of beta-thromboglobulin (beta-TG) were followed in 10 subjects with essential hypertension without any manifest vascular complications and in 14 age-matched normotensive controls. The effects of prazosin on blood pressure and platelet function were also examined in the subjects with hypertension. Platelet aggregation in response to 5 microM ADP was significantly greater in the subjects with hypertension than in the controls. Plasma beta-TG levels were 30% higher in the subjects with hypertension than in the controls. The increased platelet aggregation and plasma levels of beta-TG in the subjects with hypertension returned to normal after the blood pressure had been controlled by prazosin therapy. Our data suggest that the aggregation and release reactions of platelets increase in uncomplicated essential hypertension, and that prazosin may have some beneficial effects on the prevention of vascular complications in hypertension by normalizing platelet function as well as by lowering blood pressure.