Beta-thromboglobulin and platelet aggregation in essential hypertension and the influence of prazosin therapy

Plasma levels of beta-thromboglobulin, initial and total platelet aggregation (induced by adrenaline or ADP) were determined in twenty-eight normotensive subjects and thirty patients with untreated essential hypertension. After 7 days of treatment with prazosin in a dose of 2-8 mg daily the above measurements were repeated in eighteen essential hypertensive patients. A significant increase in plasma levels of beta-thromboglobulin, initial and total adrenaline- and ADP-induced platelet aggregation was found in hypertensives. Prazosin restored the mean arterial blood pressure in hypertensives to normal, but it had no significant influence either on increased beta-thromboglobulin levels or on platelet aggregation. The results show that increased in vivo activation as well as increased platelet aggregation need not be restored to normal after effective decrease of blood pressure. The results suggest that a combination of drugs with an antihypertensive and antiplatelet (antiaggregating) effect (or use of a drug with both an antihypertensive and antiaggregating effect) can further decrease the development of severe complications of essential hypertension.