Intravenous beta-blockade with propranolol reduced meal-induced thermogenesis from 9.6% to 7.1% (P<0.04), providing evidence of an epinephrine-mediated facultative thermogenic component in muscle.
Does intravenous propranolol reduce carbohydrate-induced thermogenesis in human skeletal muscle?
Epinephrine mediates a facultative thermogenic component in human skeletal muscle via beta-2 adrenoceptors following carbohydrate ingestion.
Absolute Event Rate: 7.1% vs 9.6%
p-value: p=<0.04
The thermic effect of carbohydrate has a component mediated by the sympathoadrenal system but of unknown anatomical localization. We have studied the contribution of skeletal muscle to the thermic effect of a carbohydrate-rich natural meal (115 g of carbohydrate, approximately 80% of energy) by means of the forearm technique on two occasions, with and without intravenous beta-blockade with propranolol. The meal-induced thermogenesis was reduced from 9.6 to 7.1% by beta-blockade (P less than 0.04), the major difference was found 90 to 240 min after the meal. The postprandial increments in plasma glucose and lactate did not change by beta-blockade, but there was a trend toward a decreased insulin response (P = 0.06). The carbohydrate-induced increase in forearm oxygen consumption was reduced by 23% after beta-blockade (P less than 0.05), the entire difference being present 90-180 min postprandially and coinciding with the peak in arterial epinephrine. The present study provides evidence of a facultative thermogenic component in skeletal muscle, mediated by epinephrine via beta 2-adrenoreceptors. However, it also points to a nonmuscle component mediated through beta 1-adrenoceptors by norepinephrine released from the sympathetic nervous system. Consequently, the sympathoadrenal system seems to play a physiological role in the daily energy balance.
Astrup et al. (Fri,) reported a other. Intravenous propranolol vs. No beta-blockade was evaluated on Meal-induced thermogenesis (p=<0.04). Intravenous beta-blockade with propranolol reduced meal-induced thermogenesis from 9.6% to 7.1% (P<0.04), providing evidence of an epinephrine-mediated facultative thermogenic component in muscle.