4.58 [nfluenoe of Inanition ox Metabolism. 



In tlio discussion of the creatinine output (see p. 389) the interpretation of 

 the results obtained in these experiments viewed in the light of the Folin theory 

 of protein metabolism was pointed out. The attempts to harmonize the results 

 of the fasting experiments with this theory showed that, while the body during 

 fasting may protect reserve tissue protein to a greater extent than during 

 ordinary conditions of nutrition, there is also the possibility that fasting may 

 result in a greater encroachment upon stored organized body material. The 

 fact that the total creatinine output remained constant even during a 7-day 

 fast was taken as an indication that no greater drafts were made upon organ- 

 ized protein than during complete nutrition. 



The presence of preformed creatine in the urine of fasting man was con- 

 sidered the result of a decrease in the power of the body to dehydrate the 

 creatine resulting from protein katabolism. In support of this view is the 

 remarkable fact that the total creatinine elimination, i. e., preformed creatinine 

 plus preformed creatine (expressed in terms of creatinine), remains constant 

 throughout the fast. Without losing sight of the possibility of this expla- 

 nation, it is of interest to consider another possible correlation of these data. 



The exact nature of the endogenous protein katabolism is not known. That 

 it is essentially different from the exogenous is by no means inconceivable, and 

 if the assumption is made that tissue protoplasm is broken down, the marked 

 decrease in the total protein katabolism during prolonged fasting would imply 

 that the katabolism of tissue protein would likewise decrease. The total 

 creatinine output considered in the light of the foregoing discussion then 

 would indicate that the tissue katabolism was supplemented by some other 

 source of creatinine. 



As a matter of fact the preformed creatinine elimination decreases as the 

 fast progresses and the preformed creatine increases. The presence of con- 

 siderable amounts of creatine in flesh would suggest that in the katabolism of 

 body flesh during inanition this creatine was liberated and that it was excreted 

 by the body as such. This involves no assumption regarding the source of the 

 preformed creatinine excreted during inanition. This latter may be derived 

 from the katabolism of protein or it may be taken from the preformed creatine 

 in the muscle, dehydrated to creatinine and so excreted, but, unfortunately, no 

 evidence is at hand to show clearly this phase of intermediary metabolism. 



The suggestion above, therefore, assumes that the so-called endogenous 

 protein katabolism during inanition decreases as the fast progresses, using the 

 preformed creatinine excretion as the measure of endogenous katabolism. The 

 excretion of preformed creatine indicates the katabolism of flesh. 



According to the results of Van Hoogenhuyze and Verploegh (11), each 

 kilogram of flesh contains not far from 4.2 grams of creatine. 14 * 3 In the later 



'"aGrindley: Jour, of Biol. Chem. (1907), 2, p. 4, has recently found 4.1 grams of 

 creatine in one kilogram of lean beef. 



