508 ADVENTURES IX RADIOISOTOPE RESEARCH 



Since the total acid soluble P content of the corpuscles is about 80 

 mgm per cent, an increase in the P content of the corpuscles amounting 

 to 5 mgm increases the total P content of the erythrocytes with 6 per 

 cent, only(^). 



In contrast to the excess phosphate added, the plasma ^^P gets distri- 

 buted between most or all of the acid soluble P of the plasma and the total 

 acid soluble P of the corpuscles. The organic molecules undergo enzymatic 

 degradation and resynthesis and, in the course of this process, a replace- 

 ment of organic P by inorganic P and, thus, by labelled P takes place. 

 An increase in the amount of organic P compounds necessitates besides 

 the presence of P excess an excess of all other ingredients necessary to 

 the formation of such compounds. These are, however, available to a 

 small extent only in the corpuscles. This fact makes it easily under- 

 standable that the whole plasma P ultimately interchanges with corpuscle 

 P, while an increase in the concentration of plasma P leads but to a 

 minor increase in the concentration of the total corpuscle P. 



RATE OF PHOSPHATE ACCUMULATION IN THE CORPUSCLES 



From the fact that, after the lapse of a few hours, the specific activity 

 of the free P of the corpuscles does not differ to any appreciable extent 

 from the specific activity of most of the acid soluble organic P fractions 

 present in the corpuscles, while the specific activity of the free plasma P 

 is found to be much higher than the specific activity of the corpuscle P, 

 we have drawn the conclusion that the penetration of phosphate through 

 the corpuscle membrane is a fairly slow process. This result was checked 

 by measuring the rate of intrusion of excess phosphate added to blood 

 into the corpuscles. The phosphate concentration of rabbit plasma was 

 raised by addition of phosphate buffer from 3.7 to 16.5 mgm per cent 



Table 13. — Rate of Penetration of Excess 

 Phosphate added to Blood into the Corpuscles 



Time in min 



Inorganic P con- 

 tent of plasma 

 in mgm. per cent 





 13.5 

 52.5 

 141 



16.5 

 16.3 

 15.6 

 14.4 



^1^ In carrying out the above calculations, the blood is assumed to be made up 

 of two parts of plasma and one part of corpuscles. 



