Alteration of beta-adrenoceptor function in hypertensive patients with different degrees of left ventricular hypertrophy.

Abstract

Previous assessment of beta-adrenoceptor function has shown alterations in essential hypertension (EH). In the present study, we compared lymphocyte beta-adrenoceptor density (Bmax) and adenylate cyclase (AC) activity stimulated by l-isoproterenol, Gpp(NH)p, Gpp(NH)p + l-isoproterenol, and forskolin in 46 patients with EH and in 17 normotensive subjects. The patients with EH were divided into two subgroups, one with left ventricular myocardial mass (LVMM) less than 200 g and the second with LVMM greater than 200 g (according to Teichholz' formula). There were no significant differences in Bmax or in AC activity [basal and stimulated by Gpp(NH)p and forskolin] between the patients and the normotensive subjects. Adenylate cyclase activity stimulated by l-isoproterenol was reduced (% from basal AC) in the patients (P less than .05), and Bmax was increased only in the patients with left ventricular hypertrophy (P less than .05). There were no differences in AC activity between the two patient subgroups, and Bmax and AC activity did not correlate with blood pressure in either the patients or the normotensive subjects. Correlations were found between Bmax and LVMM (r = 0.38, P less than .02) and between Bmax and interventricular septum thickness (r = 0.412, P less than .02) among the patients. Thus, beta-adrenergic-mediated AC sensitivity to catecholamines is reduced in patients with EH and may represent a generalized defect in beta-receptor function in EH. Increased Bmax is likely to characterize more pronounced involvement of the target organs in the pathologic process associated with EH than is a higher blood pressure level.