MAI K OK PEXETHATTON OF PIIOSI'HATK INTO Ml'SCLK CELLS 



451 



to be 2.6 per cfMit. Thus, the amount of^^p incorporated into all phospho- 

 rus fractions present in the muscle is, after the lapse of 4 days, but 

 5 per cent larger than the amount incorporated into the acid soluble 

 compounds. Jn (experiments of shorter duration thf^ difference is still h^ss. 



Table 3. — Distrihution of *-P between the Total Cellu- 

 lar Acid Soluble Phosphate Extracted from 1 gm Gastroc- 

 nemius AND the Inorganic Phosphate Extracted from 1 gm 



Plasma 



In Table 3, the distribution coefficient of ^sp between cellular P and 

 plasma P arrived at by the two different methods is given. Column 2 

 contains the distribution coefficient calculated from the ^-P content of 

 the organic fractions and of the inorganic phosphate content of the 

 muscle, as described on p. 449, while in column 3 the results are given 

 which were obtained by comparing the activity of the muscle tissue with 

 that of the plasma. The results obtained agree fairly well. 



It is of interest to remark that the labelled phosphate was found 

 to penetrate at a faster rate into the cells of mammalian muscle than 

 in those of the frog (Hahn et al., 1939). The ratio of the ^ap content 

 of 1 gm gastrocnemius and of 1 gm plasma of the rabbit; was found 

 after the lapse of 4 hours to be 0.6. 



DISCUSSION 



The concentration of the inorganic phosphate present in the water 

 of the muscle cells is about 100 times larger than that present in the 

 plasma water. This puzzling difference can be explained in two different 

 ways. We can assume that most of the inorganic phosphorus extracted 

 after a most careful treatment of the muscle was not present as inorganic 

 phosphate previous to extraction in the muscle but in the form of a 

 very labile phosphorus compound. Creatinephosphoric acid is a fairly 

 labile compound which can only be extracted without decomposition 

 if the operation is carried out at a low temperature and a very fast 



29* 



