Intestinal loss of creatine by normal and vitamin E-deficient rabbits

Abstract

The distribution of radioactivity after an intravenous injection of creatine-1-C14 was used to estimate loss of creatine. Both the control and vitamin E-deficient rabbits lost creatine into the intestine with as much as 25% of the initial dose of creatine-1-C14 being recovered from the gastrointestinal tract and its contents. Destruction of creatine in the colon was confirmed by finding large quantities of radioactivity in expired CO2 soon after an injection of creatine-1-C14 directly into the ascending colon. In 4-hr balance studies very little of the intravenously injected creatine-1-C14 appeared in the urine of control rabbits, whereas 28–48% of the initial dose was present in the urine of vitamin E-deficient rabbits. Despite the large proportion of creatine-C14 lost in the urine, the vitamin E-deficient rabbits had specific activities of muscle creatine as high as the control values. The latter observation was presumed to be the result of a low concentration and short turnover time of muscle creatine in vitamin E-deficient rabbits.