396 



ADVENTURES IN RADIOISOTOPE RESEARCH 



tered. When the 228 non-precipitated counts are considered, the specific 

 activity of the creatine P fraction works out to be 14.1 instead of 15.6. 



The same technique was used in the following experiments. 



The lowest value found for the percentage renewal of creatinephos- 

 phoric acid molecules in the course of 4 hours at 0° is 9 and in the course 

 of 17.5 hours 10 while, in most experiments, appreciably larger figures 

 were found. The rate of renewal of the creatinephosphoric acid molecules 



Table 13. — Specific Activity of Phosphorus Frac- 

 tions Extracted from the Gastrocnemius of a Frog 

 40 Hours after Injecting Labelled Sodium 

 Phosphate. Temp.: 2° 



Fraction 



JBelative specific 

 activity 



I. Inorganic P 



II. Inorganic -{- creatine P 



III. Creatine P (calculated a.s II — I) 



IV. Creatine P (determined) 



V. Pyrophosphate -f- hexose P ... 



VI. Acid soluble residual P 



VII. Non acid soluble P 



100 

 (32.7 

 33.7 

 34.4 

 22.8 

 11.3 

 2.1 



Table 14. — Specific Activity of Phosphorus Frac- 

 tions Extracted from the Gastrocnemius of a frog 

 24 Hours after Injecting Labelled Sodium 

 Phosphate. Temp.: 20° 



Fraction 



Relative specific 

 activity 



Inorganic P 



Creatine P 



P hydrolysed in the course of 1 lionr 

 Acid soluble residual P 



100 

 9.5 

 91 

 36 



Table 15. — Specific Activity of Phosphorus Frac- 

 tions Extracted from the Gastrocnemius of a Frog 

 400 Hours after In.jecting Labelled Sodium 

 Phosphate. Temp.: 20° 



Fraction 



Inorganic P 



Creatine P 



P hydrolysed in the course of 1 hour 

 Non acid soluble P 



Relative specific 

 activity 



100 

 99 



87 

 16 



