Plasma concentrations of 6-keto-prostaglandin F1.ALPHA., thromboxane B2 and platelet aggregation in patients with essential hypertension.

Abstract

Plasma concentrations of 6-keto-prostaglandin F1.alpha. (6-keto-PGF1.alpha.) and thromboxane B2 (TXB2), the stable nonenzymatic metabolites of prostacyclin and TXA2, respectively, were assayed in 26 patients with essential hypertension and 25 normotensive subjects to investigate the pathophysiological role of prostacyclin and thromboxane A2 (TXA2) in essential hypertension. A tourniquet test was also performed on the upper limb of each subject to study the reactivity in peripheral vessels. Platelet aggregation was also investigated. There were significantly increased plasma TXB2 concentrations and platelet aggregation and significantly decreased plasma 6-keto-PGF1.alpha. concentrations in patients with essential hypertension as compared with normotensive subjects. The responses to tourniquet tests were also different. There were significantly increased plasma concentrations of 6-keto-PGF1.alpha. and TXB2 and platelet aggregation in normotensive subjects, but no significant changes with essential hypertension as compared to resting values. The reduction of plasma prostacyclin and increase of plasma TXA2 may contribute to the maintenance of blood pressure elevation in patients with essential hypertension. Increased prostacyclin generation in normotensive subjects during the tourniquet test may be a protective mechanism. In patients with essential hypertension, the protective activity is reduced.