1. In six patients with hypertriglyceridaemia presenting whilst receiving treatment with β-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 β-blocker and 22.8 ± 4.8 min after stopping β-blocker treatment.
2. In three of these patients subsequent administration of a β-blocker with intrinsic sympathomimetic activity had no effect on t1/2.
3. In a cross-over trial of placebo, atenolol (β1-blocker), propranolol (β1- and β2-blocker) and pindolol (β1- and β2-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.
4. The concentrations of serum triglycerides and very low density lipoprotein cholesterol in the normal men were, however, increased by β-blockade, most markedly by pindolol.
5. Serum high density lipoprotein (HDL) cholesterol concentration decreased in normal men on β-blockers, most clearly on atenolol and propranolol. This decrease was due to a reduction in cholesterol in the HDL2 subfraction.
6. No statistically significant effects on serum low density lipoprotein cholesterol or apolipoprotein B concentrations occurred in the normal men.
7. The doses of atenolol and propranolol used in this study were equipotent as judged by the heart rate response to exercise.