474 ADVENTURES IX RADIOISOTOPE RESEARCH 



corresponding figure amounts, in the case of rats' l>lood, to only 30. 

 The average ester P content of human blood corpuscles is stated to be 

 20 mgm per 100 cc. blood, of which about 68% is present as phospho- 

 glycerate, 21% as hexosephosphate, and 11% as adenyltriphosphate/^> 

 Few data are available as to the phosphorus ester content of the plasma 

 and its composition, the presence of small amounts of hexosemono- 

 phosphate being recorded^^). The phosphoric ester content of the plasma 

 varies within wide limits, the average value being about 0.5 mgm% 

 In the normal human plasma values varying between 0.0 and 0.9 mgm% 

 and an average valve of 0.33 mgm% were recorded^^). 



DIFFUSION OF PHOSPHATE IONS INTO THE CORPUSCLES 



Radioactive sodium phosphate containing a negligi))le amount of 

 phosphorus is added to 10 cc. of heparinised rabbit blood. The sample 

 is shaken in a thermostat at 37° under a mixture of oxygen and carbon 

 dioxide, after the lapse of few hours plasma and corpuscles are sepa- 

 rated by centrifuging, the corpuscles washed 2 — 3 times with a physio- 

 logical sodium chloride solution. The acid soluble components of the 

 plasma and also those of the corpuscles are isolated in the usual way 

 (extraction with ice-cold trichloro-acetic acid). While the acid-soluble 

 fraction of the plasma is practically (90% or more) composed of in- 

 organic P, the corpuscles contain mostly organic phosphorus compounds 

 and, in addition, some inorganic P. The latter can be isolated by pre- 

 cipitation as ammonium magnesium phosphate. The organic phosphorus 

 compounds present in the filtrate are then converted into inorganic salts 

 and precipitated as such. 



When carrying out such experiments, we find that in the course of 

 few hours an appreciable part of the labelled plasma inorganic phosphate 

 penetrates into the corpuscles. At the same time we find a formation of 

 labelled organic phosphorus compounds in the corpuscles. What actually 

 happens is that the individual inorganic phosphate ions of the plasma 

 diffuse into the corpuscles and are converted in the latter into phosphorus 

 esters. The question, which now occurs, is which is the faster process, 

 the diffusion of HPOl into the corpuscles or the ester formation. This 

 can be decided by comparing the specific activities of the different 

 phosphorus fractions isolated from the corpuscles. Such a comparison 

 is seen in Table 1. After the lapse of only half an hour about half the 



^i) E. Warweg and G. Stearns, J. Biol. Chem. 115, 567 (1936). 

 S. E. Kerr and A. Antaki, J. Biol. Chem. 121, 531 (1927). 

 ^^^ Comp. li. RoBisoN, The Significance of Phosphoric Esters in Metabolism 

 p. 69. New York (1932). 



(3) R. T. Brain, H. D. Kay and P. G. Marshall, Biochem. J. 22, 635 (1928). 



