The influence of the induction of alloxan-diabetes on the incorporation of amino acids into protein of rat diaphragm

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Abstract
The effect of different treatments of the rat on the metabolism of its diaphragm, in vitro, were studied with respect to the uptake of glucose, the incorporation of [C14] glycine into protein, and the effect of addition in vitro of insulin. Two days after the administration of a diabetogenic dose of alloxan the fasting blood sugar of rats was usually about 500 mg/100 ml. Blood plasma from such animals contained no detectable insulin. Incorporation of amino acid in vitro by their diaphragms was above normal. Two weeks or more after diabetes-inducing treatment with alloxan the fasting blood sugar averaged 215 mg/100 ml. Plasma from these animals had no observable effect on the glucose uptake by isolated diaphragm from the normal rat. Untreated plasma and plasma which had been frozen and thawed stimulated incorporation of [C14]glycine into protein of diaphragm from the normal rat, though less than did plasma from the normal rat. Two days after the administration of alloxan to the intact or the hypophysectomized rat incorporation of [C14]glycine into protein of diaphragm was significantly greater than that with diaphragm from animals not so treated. Two days after the administration of alloxan to the adrenalectomized rat incorporation of [C14]glycine into protein of the animal''s diaphragm in vitro was similar to that with diaphragm from the untreated adrenalectomized rat. Treatment of the intact rat with adrenaline or with cortisol failed to mimic the effect of the administration of alloxan in stimulating the incorporation of [C14]glycine in vitro into protein of isolated diaphragm. With diaphragm from rats which had received diabetes-inducing treatment with alloxan 2 or more weeks previously, basal uptake of glucose and basal incorporation of [C14]glycine were both slightly less than with diaphragm from the normal rat, but the effect of insulin in vitro on these processes was normal. Treatment of the diabetic rat with insulin for 5 days raised the basal incorporation of glycine in vitro to about that for diaphragm from the intact rat.