Effects of Growth Hormone on Glucose Utilization in Diaphragm Muscle in the Absence of Increased Lipolysis

Three hr after the intravenous injection of 100 μg of growth hormone to hypophysectomized rats, there is a diminution in glucose uptake by diaphragm muscle in vitro. No evidence for increased mobilization of FFA from adipose tissue of the same animals was revealed by measurement of FFA and glycerol production in vitro or the content of FFA in the adipose tissue at the time of excision. Treatment of the rats with actinomycin blocked the decrease in glucose uptake caused by growth hormone. Hemidiaphragms from growth hormone-treated rats were refractory to the insulin-like action of growth hormone in vitro. Refractoriness was partially overcome by actinomycin. These data suggest that the effects of growth hormone on glucose utilization in diaphragm muscle are not mediated by increased mobilization of FFA, but rather may reflect a hormone-induced changed in genetic expression. (Endocrinology81: 1099, 1967)