Long-term beta 1-selective adrenergic blockade and adrenergic receptors in human subcutaneous adipocytes.
The influence of beta-adrenergic blockade with metoprolol, a beta 1-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 beta-adrenergic blockade and an antihypertensive effect, resulted in a significant increase (p less than 0.05) in the binding of the beta-adrenergic antagonist (-)-(3H)-dihydroalprenolol and a 50% increase (p less than 0.01) in the maximum lipolytic response to the beta-adrenergic agonist isopropylnoradrenaline. In 7 patients with normotriglyceridaemia the total plasma triglyceride level increased significantly (p less than 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 beta 1-selective adrenergic blocker metoprolol leads to a significant increase in beta-adrenoceptor density and an increase in the lipolytic response to beta-adrenergic agonists. This latter finding may, in some measure, account for the increased plasma triglyceride level observed.