Originally communicated in Nature 141, 1097 (1938) 



36. MOLECULAR REJUVENATION OF MUSCLE TISSUE 



G. Hevesy and 0. Rebbe 

 From the Institute of Theoretical Physics and the Zoophysiological Laboratory 



University of Copenhagen 



The decomposition of creatine phosphoric acid during muscular action 

 and its rebuilding during rest, has been the subject of numerous detailed 

 investigations. We were interested in the problem, if, and to what 

 extent, creatine phosphoric acid molecules are decomposed and after- 

 wards rebuilt, or 'rejuvenated', in the resting muscle. This problem can 

 be easily solved by injecting labelled sodium phosphate, for example, 

 into frogs, and determining if, and to what extent, creatine phosphoric 

 acid extracted from the muscle of the frog becomes labelled (radioactive). 

 Phosphorus atoms present in creatine phosphoric acid and other organic 

 compounds do not exchange spontaneously with other phosphorus 

 atoms present, and thus the fact that labelled creatine phosphoric 

 acid can be isolated from the muscle is a proof that this was synthesized 

 after the administration of labelled sodium phosphate. 



The muscle was placed at once after removal in liquid air, the acid 

 soluble components extracted with trichloracetic acid kept at —9°, 

 and the inorganic phosphate present in the solution precipitated as 

 ammonium magnesium salt. The next step was the decomposition 

 of creatine phosphoric acid remaining in the filtrate from the last- 

 mentioned precipitate. The decomposition was carried out by adding(^> 

 sulphuric acid (1??) and ammonium molybdate (1 per cent) to the solution. 

 The phosphate ions were then precipitated as ammonium magnesium 

 salt. The phosphorus content of the latter was determined by the colori- 

 metric method of Fiske and Subbarow, and its radioactivity by making 

 use of a Geiger counter. The results obtained for this and some other 

 fractions are seen in the accompanying table. 



A specific activity of the creatine phosphoric acid phosphorus amount- 

 ing to 49 per cent of that of the inorganic phosphorus indicates that 

 49 per cent of the creatine phosphoric acid molecules present in the 

 resting muscle were split and newly synthesized through enzymatic 

 action in the course of the last 3 hours before the frog was killed. As the 

 total number of creatine phosphoric acid molecules present in the muscle 

 can be assumed not to have changed during that time, in the resting 



