10 



Scientific Proceedings (50). 



7 (703) 



The creatine content of muscle under normal conditions. 

 Its relation to the urinary creatinine. 



By Victor C. Myers and Morris S. Fine. 



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

 Graduate Medical School and Hospital.] 



Though an unusual amount of attention has been devoted to 

 urinary creatinine since the introduction of Folin's simple colori- 

 metric method for its estimation in 1904, relatively little considera- 

 tion has been given to the supposedly related muscle creatine. 

 The few figures which have been published giving the content of 

 muscle creatine have simply served to indicate that the creatine 

 content of vertebrate muscle is in round numbers .4 per cent., 

 though figures for different animals have shown individual results 

 varying from .3--5 per cent. We have estimated the creatine 

 concentration of muscle in a number of the common laboratory 

 animals, rabbit, dog, cat, guinea pig, monkey, and likewise in 

 man, in a few instances, where we have been able to obtain good 

 samples at autopsy. Our muscle analyses on 20 normal rabbits 

 and 5 dogs have yielded very uniform figures and indicate that the 

 creatine concentration of rabbit muscle is .52 per cent, and of the 

 dog muscle, .37 per cent. Our data on the muscle of the other 

 species are as yet insufficient to warrant special comment. This 

 uniformity recalls the constancy of the daily creatinine elimination 

 first noted by Folin. 



It is a curious fact that the creatinine coefficient of the rabbit 

 is fully a third higher than that generally found in man and various 

 experimental animals, dog, pig, and guinea pig. In forty rabbits, 

 the average coefficient has been found to be 14.3 while for a healthy 

 man, the normal coefficient is about 9, and for the dog, the average 

 is probably a little lower (for 3 animals it was found to average 8.4). 

 Comparing these values with those for the creatine concentration 

 of the muscle (rabbit .52, man .39 and dog .37 per cent.), an 

 interesting, and, as we believe, more than an accidental relation- 

 ship is revealed. 



