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

ABSTRACT. Wahrenberg H, Arner P, Engfeldt P, Haglund K, RÖssner S, Östman J. (Department of Internal Medicine and Research Centre, Huddinge Hospital, Karolinska Institute, Huddinge, and Department of Internal Medicine, Karolinska Hospital, and King Gustaf V Research Institute, Stockholm, Sweden.) Long-term β₁-selective adrenergic blockade and adrenergic receptors in human subcutaneous adipocytes. The influence of β-adrenergic blockade with metoprolol, a β₁-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 β-adrenergic blockade and an antihypertensive effect, resulted in a significant increase (p<0.05) in the binding of the β-adrenergic antagonist (-)-(³H)-dihydroalprenolol and a 50% increase (p<0.01) in the maximum lipolytic response to the β-adrenergic 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 β₁-selective adrenergic blocker metoprolol leads to a significant increase in β-adrenoceptor density and an increase in the lipolytic response to β-adrenergic agonists. This latter finding may, in some measure, account for the increased plasma triglyceride level observed.