INFLUENCE OF GROWTH HORMONE ON SPLANCHNIC GLUCOSE PRODUCTION IN MAN

Abstract

ABSTRACT The influence of growth hormone (GH) on splanchnic exchange of glucose and glucogenic precursors was investigated in 11 healthy subjects using the hepatic venous catheter technique. GH was infused intravenously at the rate of 40 μg/kg body weight over 30 min. A peak plasma GH level of 219 ± 25 ng/ml was obtained. During GH infusion the blood glucose concentration fell slightly but significantly. In addition, the splanchnic glucose output decreased by approximately 35–40% during and immediately after GH infusion. The splanchnic uptake of the glucogenic precursors lactate, pyruvate, alanine and glycerol was not significantly influenced by GH infusion. The arterial concentration of insulin fell slightly, while the glucagon level remained unchanged during the infusion but decreased 20–30 min after the end of GH infusion. Indirect estimates of the peripheral glucose utilization indicated that GH infusion was accompanied by a 25% reduction in peripheral glucose uptake. The influence of GH on the inhibition of splanchnic glucose output induced by endogenous insulin in connection with intravenous glucose infusion (2 mg/kg/min) was studied in 6 subjects. GH infusion, given 60 min before the onset of glucose administration, did not significantly modify the splanchnic glucose output response to glucose infusion. It is concluded that a) GH may exert a direct inhibitory influence on splanchnic glucose output which is independent of changes in insulin and glucagon, b) hepatic glycogenolysis, but probably not gluconeogenesis is influenced by GH, and c) GH infusion is accompanied by decreased peripheral utilization of glucose.