Effects of Short-Term and Long-Term Treatment with Cardio-Selective and non-Selective β-Receptor Blockade on Carbohydrate and Lipid Metabolism and on Plasma Catecholamines at Rest and during Exercise

1. The effects on glucose and lipid metabolism and on plasma catecholamines at rest and during exercise, of 4 weeks treatment with non-selective β-blockade (pindolol, 15 mg daily) and with cardio-selective blockade (metoprolol, 200 mg, and acebutolol, 500 mg, respectively) were compared in different groups of hypertensive men (mean age 37 years) by single blind cross-over technique. All patients continued the treatment with either metoprolol or acebutolol for another 12–14 months.

2. All antagonists reduced blood pressures and exercise heart rates in a virtually identical manner. Whereas lipolysis was similarly inhibited by both selective β₁-antagonists and non-selective β₁-β₂-blockers, glycogenolysis in the muscle was inhibited only by non-selective β-receptor blockade.

3. The inhibition of glycogen breakdown resulted in exercise hypoglycaemia and in increases of plasma adrenaline and ACTH, which probably reflect counter-regulatory mechanisms. No major metabolic changes occurred after 12–14 months compared with 4 weeks of treatment.