RATE OF PENETKATION OF IONS INTO EllYTHROCYTES 509 



and the decrease of the phosphate content of the plasma was determined 

 at different intervals. As seen in Table 13, the excess phosphate penetrated 

 at a fairly slow rate, only, into the corpuscles. 



In certain experiments^^), inorganic P was found to leave the corpuscles 

 and to enter the plasma even though the concentration in the plasma 

 exceeded that in the corpuscles. This fact was interpreted as an indication 

 that the transfer of substances across the corpuscle membrane cannot 

 always be explained by the simple physico-chemical law of diffusion 

 from a higher to a lower concentration, even with the modification 

 described by Donnan. The correctness of this interpretation can be 

 challenged. The concentrations of inorganic phosphate in the corpuscle 

 w^ater and the plasma water differ for the same reason as the concentra- 

 tions of the chloride ions in the erythrocytes and in the plasma differ. 

 In equilibrium, 1 gm of plasma contains about twice as much chloride, 

 respectively phosphate, as 1 gm of corpuscles. If, in the course of phos- 

 phorylation processes going on in the corpuscles, inorganic phosphate 

 is made free, the equilibrium between corpuscle phosphate and plasma 

 phosphate is upset and a part of the additional phosphate migrates into 

 the plasma in spite of the fact that the phosphate concentration in the 

 plasma is higher than in the corpuscles. The migration will come to an 

 end as soon as the equilibrium ratio between plasma phosphate and cor- 

 puscle phosphate is obtained, a ratio which is somewhat less than 2, 

 as mentioned above. The phosphate content of the plasma constantly 

 changes, it increases if the phosphate taken up with the food gets absorb- 

 ed, when bone apatite gets dissolved, when organic P compounds present 

 in the tissue cells or corpuscles get decomposed, it decreases when glu- 

 cose is absorbed into the circulation, when additional ossification takes 

 place, when inorganic phosphate present in the tissue cells or in the 

 corpuscles gets incorporated into organic molecules, and so on. An increase 

 in the phosphate concentration of the plasma will lead to an influx of 

 some phosphate into the corpuscles and a decrease to a movement in 

 opposite direction. In contrast to the behaviour of chloride which res- 

 ponds almost momentarily to changes in the chloride concentration of 

 the plasma (510), phosphate does not. The rate of passage of 

 phosphate through the corpuscle membrane is fairly slow, it will take 

 an appreciable time before equilibrium between the concentration of the 

 plasma phosphate and the corpuscle phosphate is obtained. In the mean- 

 time, changes in the concentration of phosphate in the plasma will often 

 take place which are independent of the happenings going on in the cor- 

 puscles. For these reasons, the ratio of plasma phosphate and corpuscle 

 phosphate may never reach an equilibrium state but, nevertheless, the 

 transfer of phosphate across the cell membrane can well be explained 



(i>Comp. L. Halpern (1936). 



