Long‐term β₁‐Selective Adrenergic Blockade and Adrenergic Receptors in Human Subcutaneous Adipocytes

Abstract

Long-term Pl-selective adrenergic blockade and adrenergic receptors in human subcutaneous adipocytes. Acta Med Scand 1985; 217: 53946.The influence of P-adrenergic blockade with metoprolol, a B1-selective agent, on the adrenergic regulation of lipid mobilization was explored in subcutaneous adipocytes removed from 13 patients with essential hypertension. Treatment with metoprolol, which was associated with adequate B-adrenergic blockade and an antihypertensive effect, resulted in a significant increase @<0.05) in the binding of the B-adrenergic antagonist (-)-(3H)dihydroalprenolol and a 50% increase @<0.01) in the maximum lipolytic response to the Badrenergic agonist isopropylnoradrenaline. In 7 patients with normotriglyceridaemia the total plasma triglyceride level increased significantly (p<0.025) during metoprolol treatment, a change that was due to an increase in the very low density lipoprotein triglycerides. The findings suggest that chronic treatment with the B,-selective adrenergic blocker metoprolol leads to a significant increase in B-adrenoceptor density and an increase in the lipolytic response to B-adrenergic agonists. This latter finding may, in some measure, account for the increased plasma triglyceride level observed. Key words: catecholamines, lipolysis, adrenoceptors, human adipose tissue, B-adrenergic bhcking agents, essential hypertension.Abbreviations: A = adrenaline, Bo = maximum receptor number, ('*'I)-CYP = (-)-(I2'I)-cyanopindolol, (3H)-DHA = (-)-(3H)-dihydroalprenolol, EDso = half maximum effective dose, FFA = unesterified fatty acids, HDL = high density lipoprotein, ISA = intrinsic sympathomimetic activity. ISNA = isopropylnoradrenaline, Kd = index of binding affinity, NA = noradrenaline, TG = triglyceride, VLDL = very low density lipoprotein.