CREATININE. 693 



As the two bodies, creatine and creatinine, can easily be transformed 

 into each other, it has been considered for a long time that the urinary 

 creatinine is formed from the creatine of the muscles and other organs. 

 Unfortunately the authorities disagree on this question. FOLIN. in his 

 investigations found that about 80 per cent of the creatinine intro- 

 duced was again eliminated, while the creatine taken did not appear in 

 the urine as creatinine, but was partly retained by the body and in 

 part eliminated as such. An intravital transformation of creatine into 

 creatinine is disputed by v. KLERCKER, MELLANBY and LEFMANN/ while 

 it is accepted by GOTTLIEB, STANGASSINGER, S. WEBER, v. HOOGEN- 

 HUYZE and VERPLOEGH and ROTHMANN. The observations of MYERS 

 and FINE indicate a production of urinary creatinine from creatine, that is 

 they found that the creatinine elimination by the urine in rabbits was 

 greater according to the total creatine content of the respective animal. 

 The investigations of PEKELHARING and v. HOOGENHUYZE on the behavior 

 of parenterally introduced creatine in rabbits and dogs, show without 

 any doubt that a part of the creatine is actually transformed into creatinine. 

 TOWLES and VoEGTLiN 2 have also observed that the subcutaneously 

 injected creatine increases somewhat the creatinine elimination, while this 

 is not the case with creatine taken per os. The condition of the digestive 

 apparatus also seems to be of importance here. PEKELHARING and v. 

 HOOGENHUYZE found that in dogs of the parenterally introduced creatine 

 always a smaller part (as creatine and creatinine) passed into the urine 

 during the digestion than during rest of the digestive organs. They 

 explain this by the accepted ability of the liver to partly destroy the 

 creatine and partly by an anhydride formation of transforming the creatine 

 into creatinine. 



As mentioned in Chapter X the proteins and the guanidine groups 

 therein are considered as the mother-substance of these two bodies. 

 If the creatinine (creatine) originates from the protein it is evident that 

 we must differentiate between food-protein and body-protein. The quan- 

 tity of creatinine is, inasmuch as it is increased by meat diet, dependent 

 upon the food; but otherwise, as found by FOLIN and in chief substantiated 

 by others, is rather independent of the food. Its elimination does not 

 run parallel with the urea and the total nitrogen, and consequently is 

 not in general greater with food rich in protein than with food poor therein. 

 Oh the contrary, its extent, as shown by other conditions, is dependent 

 upon the intensity of the metabolism in the cells, especially the muscle 



1 Folin, Hammarsten's Festschrift, 1906; v. Klercker, Bioch. Zeitschr., 3; Mellanby, 

 Journ. of Physiol., 36; Lefmann, Zeitschr. f. physiol. Chem., 57. 



2 See footnote 1, page 574, and v. Hoogenhuyze and Verploegh, Zeitschr. f. physiol. 

 Chem., 59; Pekelharing and v. Hoogenhuyze, ibid., 69; Towles and Voegtlin, Journ. 

 of biol. Chem., 10; Myers and Fine, ibid., 14. 



