Metabolism of creatine-1-C¹⁴ by vitamin E-deficient and hyperthyroid rats

¹ Department of Biochemistry, School of Medicine, University of Arkansas, Little Rock, Arkansas

Normal, vitamin E-deficient and hyperthyroid rats were given creatine-1-C¹⁴ intraperitoneally, and its incorporation into skeletal muscle was determined. The incorporation of the creatine into skeletal muscle was increased in vitamin E-deficient rats while serum creatine-C¹⁴ activity was reduced. Hyperthyroidism led to a decreased incorporation of creatine into skeletal muscle and to elevated serum creatine-C¹⁴ levels. It is concluded that in vitamin E deficiency there is an inability of skeletal muscle to retain creatine and that in hyperthyroidism there is a block in the entry of creatine into skeletal muscle.