Creatine and carbohydrate metabolism

Abstract

The level of liver creatine in fed guinea pigs was less than 12 mg/100 g liver. A 12 hour fast increased it to 33 mg. In both cases, 25% was in the bound form. Although liver creatine is lower in rats, a similar change was observed, and also in blood and urine creatine. No evidence was found of increased creatine synthesis in the liver. Perfusion of rat heart showed no difference in loss of creatine whether from starved or fed rats. Perfusion of rat hind limbs showed an increase in creatine as glucose decreased the creatine concen-tration. Sodium iodoacetate increased the creatine level. With additions of glucose to keep its concentration constant, DNP raised the creatine in the perfusate. It is concluded that a fall in blood sugar produced a reversible loss of creatine from skeletal muscle and this is responsible for the rise in liver and urine creatine. Adrenalectomy, thiouracil, and hypophysectomy enhanced the effect of starvation on creatine. Short exposure to cold had no effect. Electrolyte balance may also influence the release of creatine from muscle.