Beta 1-adrenoreceptors regulate resting metabolic rate
Lamont, L.S.; Romito, R.A.; Finkelhor, R.S.; Kalhan, S.C.
Medicine and Science in Sports and Exercise 29(6): 769-774
1997
ISSN/ISBN: 0195-9131 PMID: 9219204 Document Number: 471490
This was a randomized, cross-over experiment designed to determine which beta-adrenergic receptors, beta-1, beta-2, or both, regulate metabolic rate in humans. All subjects (3 women, 4 men) were administered a 7-d therapeutic dose of a selective beta-1-antagonist (atenolol 50 mg BID), a combined beta-1,beta-2-antagonist (propranolol 80 mg BID), and a placebo control (BID). Indirect calorimetry was determined before and after 1 h of submaximal exercise. Exercise was performed at 50% of the trial specific ovrhdot VO-2peak because maximal exercise was significantly decreased in the presence of the nonselective beta-1, beta-2-antagonist ( ovrhdot VO-2peak placebo: 44.90 +- 4.40 mL cntdot kg-1 cntdot min-1 vs beta-1, beta-2-antagonism: 39.20 +- 3.00 mL cntdot kg-1 cntdot min-1; P lt 0.05). Both the beta-1 and the combined beta-1, beta-2-adrenoreceptor antagonists reduced resting oxygen consumption to a similar extent (0.247 +- 0.007 L cntdot min-1 placebo, vs 0.218 +- 0.007 L cntdot min-1 beta-1-antagonism, vs 0.226 +- 0.007 L cntdot min-1 beta-1,beta-2-antagonism; P lt 0.05). However, the 30-min and 60-min excess postexercise oxygen consumption (mean EPOC) remained unchanged. It is concluded that the beta-1-receptors are regulating the effects of the sympathetic nervous system on resting but not exercise recovery metabolic rate. These metabolic side effects may suggest that changes need to be made in the nutritional requirements of patients using beta-adrenergic antagonists.