472 ADVENTURES IN RADIOISOTOPE RESEARCH 



corpuscles fluctuates within wide limits. Halpern^^) investigated the in- 

 organic P content of the plasma and corpuscles of rabbit blood in 33 

 cases. In 29 cases the inorganic P content of the corpuscles was found 

 to be less than that of the plasma of equal volume, the ratio between 

 the inorganic P content of the corpuscles and that of the same volume 

 of plasma varying between 0.86 and 0.38. In our experiments we find 

 an average content of the plasma inorganic P amounting to 7 mgm % 

 and of the corpuscles inorganic P to 4.5 mgm % making the above 

 mentioned ratio equal to 0.64. When taking into account that the water 

 content of the corpuscles amount to only 70% of that of the plasma, we 

 obtain for the distribution coefficient of the inorganic P between the 

 corpuscle water and plasma water a value differing not much from 

 unity. (2) While the determination of the inorganic P of the plasma is not 

 difficult, as the acid-soluble plasma P is mostly composed of phosphate 

 ions, the analysis of the corpuscles often gives less reliable results. 

 Some of the organic phosphorus compounds present in the corpuscles 

 may decompose^^^ in the course of the formationof additional inorganic 

 phosphate. On the other hand, when the corpuscles have to be obtained 

 quite free of plasma as in our experiments, it is necessary to wash 

 them with a suitable solution free of phosphate, for example with 

 an isotonic sodium chloride solution in the course of this operation 

 some phosphate can be lost from the corpuscles by a diffusion process. 

 In view of the great importance the plasma phosphoric esters play in 

 Robison's theory of bone calcification, he and his collaborators^'*^ made 

 a careful study of the amount of phosphoric ester present in the plasma 

 from human and rabbit bloods and ascertained an average value of 

 about 0.5 mgm%. 



The problem in which we were interested was the determination of 

 the rate at which phosphate ions and also the phosphoric ester molecules 

 of the plasma penetrate into the corpuscles and vice versa. The usual 

 procedure employed to obtain information on the permeability of the 



f , 



(i^L. Halpebn, J. Biol. Chem. 114, 747 (1936). In this paper earlier literature 



on this subject is to be found. R. T. Brain, H. O. Kay and P. G. Marshall 

 [Biochem. J. 22, 628 (1927)] found the inorganic P content of the human blood 

 plasma to be 4.1 mgm. %, that of the corpuscles 2.4 mgm. %. 



(2) R. T. Brain, H. O. Kay and P. G. Marschall [Biochem. J. 22, 629 (1928)] 

 find for human blood the same distribution coefficient as found bj^ us for canine 

 blood, namely 0.91. 



(^)Maitland, Hansman and Robison [Biochem. J. 18, 1152 (1924)] have shown 

 that, of the blood is made acid to pH — 7.3, there is hydrolysis, if made alkaline 

 to pH — 7.35 there is for a short time synthesis of the esters; this, however, soon 

 gives place to hydrolysis and to a corresponding increase of the inorganic phosphate; 

 comp. also H. Lawaczeck, Biochem. Zeitsch. 145, 351, 1924. 



(*)R. Robison, The Significance of Phosphoric Esters in Metabolism, p. 68., New 

 York (1932) Comp. also R. T. Brain, H. O. Kay and P. G. Marshall, lac. cit. 



