Whole body and splanchnic metabolic and circulatory effects of glucose during beta-adrenergic receptor inhibition

The aim of the study was to assess the possible contribution of adrenergic mechanisms to the thermogenic and circulatory effects of glucose ingestion. With the use of indirect calorimetry and arterial, pulmonary arterial, and hepatic venous catheterization, whole body and splanchnic oxygen uptake and blood flow were examined in nine propranolol-treated healthy male volunteers before and during 2 h after oral ingestion of 75 g of glucose. The glucose effects were compared with those in nine untreated controls. After propranolol, the glucose-induced rise in splanchnic blood flow was reduced by similar to 60%, and the hepatic venous glucose release to the systemic circulation was significantly delayed. Glucose-induced increments in pulmonary and splanchnic oxygen uptake and cardiac output were similar in the two groups. It is concluded that adrenergic mechanisms contribute to the glucose-induced rise in splanchnic blood flow and thereby probably to the time course for intestinal absorption of nutrients. It is suggested that the magnitude of glucose-induced thermogenesis is independent of adrenergic stimulation.