Stimulation of sugar transport by a factor released from gas-perfused hearts

Abstract

When gas-perfused kitten hearts are perfused intermittently with small volumes of Krebs solution, the effluent contains a material which precipitates with 0.25 saturation with ammonium sulfate. This material increased the uptake of nonmetabolized sugars and amino acids by isolated skeletal muscle, the uptake of glucose by adipose tissue, and the deposition of glycogen in muscle. The material was different from insulin as determined by immunoassay. The increment in sugar uptake could not easily be demonstrated to be dependent on the concentration, owing to the considerable variability of the total activity and to a depressant effect appearing with higher concentrations. There appeared to be no correlation between the cardiac positive inotropic activity reported previously and the activation of membrane transport by this material. The material is very similar to the muscle activity factor described by others.