Scientific Proceedings (54). 



105 (801) 

 Further studies on muscle creatine. 



By M. S. Fine and V. C. Myers. 



[From the Laboratory of Pathological Chemistry, New York Post- 

 Graduate Medical School and Hospital.} 



In an earlier communication, 1 attention was called to the 

 constancy in the content of muscle creatine for normal animals of 

 a given species, though distinctive for different animals. It was 

 further pointed out that during starvation in the rabbit, the per- 

 centage content of muscle creatine may show either an increase or 

 a decrease, the latter depending in considerable part upon the 

 rate and amount of creatine eliminated in the urine. 



These observations have been extended to rabbits which have 

 been fed for varying periods upon carbohydrate — without fat 

 or protein. Carbohydrate feeding greatly reduces the elimination 

 of creatine in the urine, as previously observed, though the creatine 

 content of the muscle does not materially differ from that found 

 during a similar length of starvation. In other words, it may be 

 markedly decreased during a long period of carbohydrate feeding. 

 It seems probable that the action of the carbohydrate is simply 

 one phase of the sparing action of carbohydrate on protein meta- 

 bolism, in this case allowing sufficient time for the body to handle 

 the creatine, i. e., to oxidize it, or change it to creatinine. 



That creatine when fed or injected does not reappear in the 

 urine in the form of creatinine, except in traces, or in large amount 

 unchanged, unless given in considerable quantity, has been as- 

 certained by a number of investigators. The possibility that this 

 creatine, which remains unaccounted for, is stored up in the muscle 

 has not been adequately studied. In four experiments on rabbits, 

 the creatine content of the muscle, after repeated subcutaneous 

 injections of creatine, has been found to be uniformly slightly 

 above (4-7 per cent.) the normal amount. This would appear to 

 indicate that a small amount of the injected creatine was deposited 

 in the muscles, though insufficient to account for the creatine not 

 eliminated in the urine either unchanged or in the form of creati- 



1 Myers and Fine, Proc. Soc. Exp. Biol, and Med., October, 1912, X, pp. 10 

 and 12. 



