Creatine and creatinine in the carcass and urine of normal and vitamin E-deficient rabbits.

Morgulis and Spencer (1) reported that the urinary excretion of creatine was increased in vitamin E-deficient rabbits and that there was no decrease in the urinary creatinine excretion. Goettsch and Brown (2) found that the muscle content of creatine was decreased in vitamin E-deficient rabbits which indicated the creatinuria was at least in part the result of a nonretention or nonutilization of creatine by the muscle. However, Heinrich and Mattill (3) observed an increased amount of creatine in livers from vitamin E-deficient rabbits and therefore suggested that the rate of synthesis of creatine may have been increased. These authors indicated that a satisfactory solution to the problem required a complete balance sheet of liver, muscle, blood, and urinary creatine. They also stated that such studies would be greatly facilitated by less circumstantial and more precise methods of determining creatine in tissues as complex as liver, and in the blood. Additional evidence was obtained by Dinning and Fitch (4, 5) who investigated the incorporation of labeled creatine precursors into the creatine of normal and vitamin Edeficient rabbits. They concluded that the rate of creatine synthesis was, in fact, increased as the result of the dietary deficiency. It seemed that an increased rate of synthesis of creatine should be confirmed by measuring the creatine and creatinine content of the carcass and of the urine from animals that had received normal and vitamin E-deficient diets. It was found that the vitamin E-deficient rabbits excreted an increased amount of creatine and a decreased amount of creatinine in their urine, and also had a decreased amount of creatine in their carcass. In fact, the total carcass and urine creatinine and creatine of the deficient animals was slightly less than the total for the control animals. The transamidinase (the first step in creatine synthesis) activities of the kidneys and pancreas from the animals was measured in vitro. Kidneys from the rabbits that had been fed the deficient diet had, in vitro, only 40% of the activity found in kidneys from rabbits that received dietary supplements of vitamin E, whereas pancreatic transamidinase activities were not changed. These data are interpreted to indicate that creatine synthesis was not increased in the vitamin E-deficient rabbits.