Properties of alpha- and beta-adrenoceptors in circulating blood cells of patients with essential hypertension.

The properties of platelet alpha 2-adrenoceptors and of lymphocyte beta 2-adrenoceptors were determined in 40 male patients with established essential hypertension and compared with those in 40 male normotensives. The densities of platelet alpha 2-adrenoceptors (assessed by 3H-yohimbine binding) and of lymphocyte beta 2-adrenoceptors [determined by (+/-)-125iodocyanopindolol binding] were in patients with essential hypertension significantly higher than in controls; there were significant positive correlations between the mean arterial blood pressure of the subjects and alpha 2- and beta 2-adrenoceptor density, respectively. Concomitantly with receptor densities, functional responses to adrenergic stimulation were exaggerated in essential hypertension: in platelets, the aggregatory response to (-)-adrenaline (via alpha 2-adrenoceptor stimulation) was enhanced; in lymphocytes, the cyclic AMP response to (-)-isoprenaline (via beta 2-adrenoceptor stimulation) was elevated. It is concluded that the increased adrenoceptor density and responsiveness in circulating blood cells of patients with essential hypertension may reflect increased sympathetic activity, which might contribute to the elevation of blood pressure.