Hepatic lipid metabolism in experimental diabetes: I. release and uptake of triglycerides by perfused livers from normal and alloxan-diabetic rats

Abstract

The uptake of nonesterified fatty acids was accelerated and the net release of triglyceride by the isolated perfused rat liver was depressed in alloxan diabetes. Triglyceride release by livers from either normal or diabetic rats was proportional to the palmitate presented to the liver; triglyceride release, however, was depressed in livers from diabetic rats at all concentrations of perfusate fatty acid. Uptake of triglyceride from chylomicra was more rapid by livers from diabetic animals than by livers from normal fed rats. Ketone-body formation and urea production were both accelerated by diabetes and restored to normal levels by treatment with insulin of the animal from which the liver was obtained. Ketone-body output remained constant regardless of the quantity of palmitate added to the perfusion medium. Since the uptake by liver of triglycerides from chylomicra, or from a neutral fat emulsion as reported previously, was accelerated in alloxan diabetes, it was of interest to compare the rates of disappearance of a neutral fat emulsion from the blood stream of normal or diabetic rats. It was observed that the disappearance of neutral fat from the plasma of diabetic rats was delayed considerably in comparison to the normal. Insulin therapy of the animals, moreover, increased the rate of disappearance of esterified fatty acid from the blood. The uptake and release of triglyceride by the isolated perfused rat liver were discussed with reference to a mechanism for the occurrence of fatty liver and hyperlipemia in experimental diabetes.