THE EFFECT OF INSULIN ON THE DISTRIBUTION OF GLUCOSE BETWEEN THE BLOOD PLASMA AND THE LIVER IN ALLOXAN-DIABETIC AND ADRENALECTOMIZED RATS.

Abstract

In diabetic rats the concentration of glucose in the liver was less than in the plasma. The relative accumulation of glucose in the liver cell after the injection of insulin was also found to be significantly less in previously untreated diabetic than in normal rats. Pretreatment with insulin restored the response to normal. Experiments with labeled glucose indicated that the rate at which glucose is carried through the hepatic cell membrane is very high compared to the rate at which glucose is being formed in the liver cells in diabetic rats. The relatively small ;)mount of glucose acciimiilati~~g after insulin in livers of diabetic rats originates from the plasma. In adrenalectomized rats which have very little liver g.l\,cogen, the relative accumulation of glucose in liver cells, following the inject1o11 of i~~bulin, was less than that in normals. These experiments indicate that in normal rats a large part of the glucose retained in the liver after the injection of i~isuli~l originates from non-labeled endogenous hepatic sources, presumably glycogen. In an earlier series of experinlents it was found that in rats the hepatic cell water contains glucose at a concentration 2075 higher than that of plasma water (1). 'The findings, that r at liver tissue contains about as much glucose as plasnia, have been confirnled (2, 3, 5). This concentration ratio has been reported to be increased by insulin (1). This observation was proposed as an explailatiorl for tlle mechanisill by which insulin increases the tracer-deternliiled apparent distribution space in normal, but not in diabetic dogs (4). The objchctive of the experiineilts presented below was to investigate whether diabetic rats respond differently to insulin than do normals with regard to the hepatic accuin~ilatio~l of glucose; and if so, to determine tlle nature of the difference. Methods