Energy Metabolism in Diabetic Heart

Abstract

The main experimental animal model for human diabetes has been the alloxan - or streptozotocin-treated animal. Such preparations resemble human type I or insulin-dependent diabetes. Recently a rat model has been introduced that exhibits characteristics of type n or insulin-independent diabetes. This is the SHR/N-cp rat developed by C.T. Hansen at the National Institutes of Health (1) and studied in detail by Michaelis et al.(2). This animal is obese, hyperinsulinemic and hyperlipidemic. The fasting blood sugar is only slightly elevated, but the glucose tolerance curve is markedly abnormal. The diabetes manifested in this animal is thus caused not by a lack of insulin but rather by resistance to the action of the hormone. Hypertension is absent in young rats but develops slowly with age. A genetically related animal, the LA/N-lean rat, is not diabetic and is used as a control in the studies reported here. In our recent investigations of the effect of diabetes on metabolism we have used these animal models as well as the streptozotocin-diabetic rat. Our experiments have centered around glycogen metabolism, and because of the involvement of uracil nucleotides in the synthesis of glycogen, the metabolism of these intermediates has also been studied.