Modification of the metabolic and hormonal response to physical exercise by beta-blocking agents.
Beta-blockade is known to induce muscle fatigue and tendency to hypoglycaemia during prolonged exercise. In addition, beta-blocking agents influence the secretion of many hormones, which regulate glucose. We have investigated the effects of a beta 1-selective (metoprolol) and a non-selective (propranolol) beta-blocking agent on muscle glycogenolysis, blood glucose and lactate levels, plasma levels of free fatty acids and on secretion of insulin, growth hormone, glucagon and cortisol during physical exercise in a double blind cross-over study in seven healthy male volunteers. They participated in three bicycle ergometer tests each lasting for 30 minutes under treatment of placebo (C), metoprolol (M) or propranolol (P). A biopsy was obtained from the vastus lateralis muscle before and immediately after the exercise for muscle glycogen assay. The glycogen concentration after exercise tended to be lower in C than in M or P experiment. The blood glucose level decreased during P and at 30 min there was a significant difference between P and C. The blood lactate was significantly lower before exercise during P than C or M. The increase of blood lactate during exercise, however, was not inhibited by P. Both beta-blocking agents counteracted the increase of FFA during exercise. There was a marked increase of growth hormone secretion during beta-blockade. The secretion of glucagon and cortisol were slightly increased by P and M, but the plasma insulin level was not affected by beta-blockade.
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005934:Glucagon / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007773:Lactates / Q000378:metabolism; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D005082:Physical Exertion; D011412:Propanolamines / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007773:Lactates; D011412:Propanolamines; D013006:Growth Hormone; D006003:Glycogen; D005934:Glucagon; D011433:Propranolol; D008790:Metoprolol; D006854:Hydrocortisone