Characteristics of lymphocyte β-adrenoceptors in essential hypertension: Effects of propranolol treatment and dynamic exercise.

Abstract

The density of beta 2-receptors in intact lymphocytes was studied by binding with 125iodo-cyanopindolol in 18 male patients with mild or moderate hypertension before and after monotherapy with propranolol. The density of these receptors was also determined in 5 patients before and after dynamic exercise. We found that propranolol therapy evoked different changes in the density of beta-receptors in patients with essential hypertension. Based on these results, all patients were divided into two groups: (a) patients who responded to the administration of propranolol by an increase in receptor density and (b) patients who responded with a decrease in receptor density. Propranolol therapy had a pronounced hypotensive effect in the second group and no hypotensive effect in the first group. In the second group, heart rate was significantly higher initially and showed a significantly greater decrease after treatment. The initial values for beta 2-receptor density were also significantly higher in this group than in the first group. Mean values of baseline plasma renin activity (PRA) were higher in the second group, but this difference was nonsignificant. The 5 patients who participated in dynamic exercise exhibited different changes in beta-receptor density, which correlated with the changes observed with propranolol treatment. There was no correlation between PRA and the density of beta 2-receptors in lymphocytes. Positive correlations were found between the density of these receptors and left-ventricular myocardial mass and interventricular septal thickness. The data indicate that the density of these receptors in lymphocytes is regulated in a qualitatively different manner in the two groups of patients with essential hypertension; this difference appears to be related to baseline renin levels or, perhaps, catecholamine levels. Additional studies are needed to clarify the regulation of beta 2-receptors in essential hypertension.