Platelet alpha(2)-adrenoceptor alterations in patients with essential hypertension are normalized after treatment with doxazosin but not propranolol

Objective Marked alterations have been demonstrated to occur in the platele t alpha(2)-adrenoceptors of patients with essential hypertension. The purpo se of this study was to determine whether antihypertensive treatment with a lpha-adrenergic blocker doxazosin or beta-adrenergic blocker propranolol ca n affect the affinity and the density of platelet alpha(2)-adrenoceptors in such patients. Subjects and methods In two groups of 22 previously untreated, essential hy pertensive patients, the mean affinity (K-d) and density (B-max) of platele t alpha(2)-adrenoceptors were studied by [H-3]-UK 14304 binding assays; the first assays were performed before any medication was begun, the second we re performed after treatment for up to 13 weeks with doxazosin or propranol ol. A third group of 22 healthy normotensive volunteers matched by age, sex and body mass index was used as control. Results Blood pressure did not differ significantly in the two hypertensive groups, and treatment with the two drugs resulted in closely similar, norm al blood pressure levels. K-d and B-max values were significantly higher in the two hypertensive grou ps than in controls. After treatment with propranolol the binding parameter s did not change significantly, whereas after treatment with doxazosin Kd a nd B-max returned to normotensive values. Conclusions In previously untreated, essential hypertensive patients platel et alpha(2)-adrenoceptors have a lower affinity but a higher density than i n normotensive subjects Despite similar effects on blood pressure, the trea tment with the alpha-adrenergic blocker doxazosin is followed by restoratio n of normal findings in the binding assays of platelet alpha(2)-adrenocepto rs whereas the treatment with the beta-adrenergic blocker propranolol does not alter the K-d and B-max values. J Hypertens 2000, 18:217-221 (C) Lippin cott Williams & Wilkins.