[Effects of various beta-receptor blockers on metabolic and circulatory parameters during physical exertion]

For further elucidation of the effect of various beta-adrenoceptor blockers on metabolism during exercise investigations on the influence of 5 beta-adrenoceptor blockers were carried out in healthy subjects. The 5 beta-adrenoreceptor blockers (acebutolol, metoprolol, penbutolol, pindolol, propranolol) were different regarding cardioselectivity and intrinsic activity (ISA). Each substance was given in 4 different dosages corresponding to 10:20:40:80 mg propranolol. Exercise was performed as bicycle ergometer test over 1 hour. In order to find out different effects during long-term application a medium dosage corresponding to 40 mg propranolol was applied for 4 weeks after the acute trials. The following parameters were measured: heart rate, systolic arterial pressure, parameters of carbohydrate metabolism (glucose, lactate) as well as lipid metabolism (free fatty acids (FFA), cholesterol, triglycerides etc.), serum concentration; for three beta-adrenoceptor blockers hormonal concentrations (catecholamines, insulin, human growth hormone (HGH), adrenocorticotrophic hormone (ACTH] were assessed. The different beta-adrenoceptor blockers demonstrated a varying relation between dosage and effect which was mostly pronounced for propranolol. All beta-adrenoceptor blockers caused a nearly complete blockade of energy release from FFA, and serum glucose concentration decreased. These changes were smaller under the effect of a low dosage of the cardioselective beta-adrenoceptor blocker metoprolol. The hormonal concentrations demonstrated a more pronounced increase of epinephrine during beta-blockade in contrast to only small changes by norepinephrine. Whereas there was no effect to be found on ACTH, HGH increased significantly under beta-blockade but independent of cardioselectivity.(ABSTRACT TRUNCATED AT 250 WORDS)