EXERCISE METABOLISM IN HEALTHY-VOLUNTEERS TAKING CELIPROLOL, ATENOLOL, AND PLACEBO

Objective-Previous studies have show that beta(1) selective agents hav e fewer adverse effects on exercise metabolism than non-selective beta blockers, and this has been attributed to their reduced blockade of b eta(2) receptors. This study aimed at determining whether a beta block er with partial agonist activity at beta(1) and beta(2) receptors (cel iprolol) was better than a conventional beta(1) receptor-blocker (aten olol) in prolonging exercise capabilities. Methods-After four days of treatment with celiprolol 200 mg, atenolol 50 mg, or placebo, 22 healt hy volunteers exercised on a treadmill for two hours at 50% of their m aximal oxygen uptake. Resting heart rate and blood pressure were recor ded before and after exercise. During exercise, fat oxidation, plasma free fatty acids, glycerol, glucose, and ammonia were measured togethe r with heart rate and perceived exertion. Results-Mean exercising hear t rate was significantly lower in those taking either of the beta bloc kers than in those taking placebo, and significantly lower for those t aking atenolol rather than celiprolol. Fat oxidation was significantly lower for those taking celiprolol (38.8 (SD 12.2)%, P<0.01) and ateno lol (36.6 (15.9)%, P<0.01) compared with placebo (45.6 (14.1)%). For t he first 15 minutes of exercise, fat oxidation was significantly lower for those taking atenolol (24.6 (12.8)%, P<0.01) than celiprolol (29. 6 (14.3)%). The rise in plasma free fatty acids and glycerol during ex ercise was also significantly attenuated by both beta blockers in comp arison with the rise in those taking placebo (P<0.01). Conclusions-Bot h celiprolol and atenolol reduced fat oxidation compared with placebo. For the first 15 minutes of exercise fat oxidation was preserved by c eliprolol, but not atenolol. This preservation of fat oxidation during the early part of exercise may confer some small benefit to patients who take beta blockers and intend to exercise regularly. However, we d id not detect significant differences between atenolol and celiprolol in overall mean fat oxidation or perceived exertion in this study.