Short-term effects of beta-adrenoceptor blocking drugs with and without cardioselectivity and intrinsic sympathomimetic activity on lipoprotein metabolism in hypertriglyceridaemic patients and in normal men.

In six patients with hypertriglyceridaemia presenting whilst receiving treatment with beta-adrenoreceptor blocking drugs (mean serum triglycerides 31.2 mmol/l) the half-life (t1/2) of an intravenously administered triglyceride emulsion was 32.8 +/- 7.9 min (mean +/- SEM) on beta-blocker and 22.8 +/- 4.8 min after stopping beta-blocker treatment. In three of these patients subsequent administration of a beta-blocker with intrinsic sympathomimetic activity had no effect on t1/2. In a cross-over trial of placebo, atenolol (beta 1-blocker), propranolol (beta 1- and beta 2-blocker) and pindolol (beta 1- and beta 2-blocker with intrinsic sympathomimetic activity) in 11 normal men t1/2 was 11.8 +/- 0.9, 12.6 +/- 1.1, 14.3 +/- 1.7 and 12.4 +/- 1.1 min respectively. None of the apparent differences achieved statistical significance, but in two men marked increases in t1/2 occurred on propranolol. The concentrations of serum triglycerides and very low density lipoprotein cholesterol in the normal men were, however, increased by beta-blockade, most markedly by pindolol. Serum high density lipoprotein (HDL) cholesterol concentration decreased in normal men on beta-blockers, most clearly on atenolol and propranolol. This decrease was due to a reduction in cholesterol in the HDL2 subfraction. No statistically significant effects on serum low density lipoprotein cholesterol or apolipoprotein B concentrations occurred in the normal men. The doses of atenolol and propranolol used in this study were equipotent as judged by the heart rate response to exercise.