Influence of propranolol on the acute thermic effect of feeding in man

The influence of a beta-adrenergic blocker on the thermic effect of feeding (TEF) a meal was investigated in 7 healthy male volunteers. Metabolic rate (MR) was measured before and for 180 min after the consumption of 2.0 MJ 'Ensure' (Abbott Laboratories, Queensborough, Kent, UK); there were 14, 33 and 53% of energy from protein, fat and carbohydrate, respectively. On one occasion propranolol (ICI plc, Macclesfield, Ches., UK) was administered intravenously at 0.1 mg/kg body weight at meal feeding. On the second occasion a similar volume of saline was infused. Serial blood samples (10 ml) were collected before and at 30-min intervals for 180 min after meal feeding. Mean (+/- SD) resting MR was 104 (13) and 116 (11) kJ/kg and MR increased by 12.8% and 10.8% after the test meal with and without propranolol, respectively. These differences were not significant. The postprandial changes in serum glucose and triiodothyronine were similar in the two trials. The magnitude of the rise of serum insulin was similar in the two trials, but the pattern was not. beta-Adrenergenic blockade resulted in an early peak in insulin output at 30 min compared with 60 min for the control trial. We conclude that propranolol had no influence on TEF in this study.