Effects of ketanserin on platelet function and red cell filterability in hypertension and peripheral vascular disease.

Serotonin is a vasoactive substance that acts on blood vessels and platelets but whose primary action lies in its role as an amplifier for other agents. The aim of this work was to study the effects on blood platelets and erythrocytes of the S2-serotonergic receptor antagonist ketanserin. Twenty-seven patients with untreated hypertension and/or intermittent claudication received a bolus intravenous (i.v.) injection of 10 mg ketanserin followed by 2 mg/h during 3 h i.v. infusion. Platelet function and erythrocyte filterability were studied before and 30 min, 3 h, and 24 h after the bolus injection. The results showed decreases of plasma beta-thromboglobulin and platelet factor 4 levels (p less than 0.001) and platelet aggregation induced by epinephrine plus serotonin (p less than 0.001), whereas ADP-induced aggregation remained unchanged 30 min and 3 h after ketanserin administration. Red cell filterability was decreased (p less than 0.01). There was a tendency toward lower mean arterial blood pressure but heart rate remained unchanged. The dual effect of ketanserin on platelet function and erythrocyte filterability might be of great clinical value in hypertension and peripheral vascular disease in which microcirculatory flow is altered.