Carcass Transamidinase Activities, in vitro, and Rates of Creatine Synthesis, in vivo, in Normal and Protein-depleted Rats

Abstract
Experiments were conducted in an attempt to determine whether there was any correlation between carcass transamidinase activities, in vitro, and rates of creatine synthesis, in vivo. Protein depletion was the method used to produce alterations in the transamidinase activities. Rats were fed either complete or protein-free diets for a period of 7 days and then given intraperitoneal injections of solutions of glucose, or arginine plus glycine. Carcass transamidinase activities, in vitro, and the amounts of creatine and creatinine in the urine and carcasses were determined. The difference in the amounts of creatine plus creatinine between the rats injected with arginine-glycine and the glucose-injected rats was defined as the rate of creatine synthesis, in vivo. There was a good correlation between rates of creatine synthesis, in vivo, and carcass transamidinase activities, in vitro, that is, both measurements were 2 times as great in the rats fed the complete diet as in the rats fed the protein-free diet.