494 



ADVENTURES IN RADIOISOTOPE RESEARCH 



content of the sodium chloride solution and of a plasma sample by Kjel- 

 dahl's method. From the figures obtained the amount of plasma present 

 in the sodium chloride solution was calculated to be 3 per cent of the 

 plasma content of the blood. This is the upper limit of the percentage 

 plasma adhering to the centrifuged corpuscles, since some corpuscle 



Distribution 

 Coefficient 



90min. 



FiG. 1. Distribution of labelled ions between corpuscles and plasma 

 of equal weight at 37°. (Rabbit blood was used in the experiments 

 with chloride and phosphate, dog blood^'^ in the experiments with 

 sodium. The ordinate indicates the distribution coefficient of the 

 labelled ion between corpuscles and plasma of equal weight.) 



nitrogen may have leaked into the sodium chloride solution during 

 the washing procedure. 



Another method to test the amount of plasma adhering to the cor- 

 puscles is the following. Labelled phosphate is added to blood kept at 

 0° and the blood sample is centrifuged at once. When plasma adheres 

 to the corpuscles the corresponding amount of labelled phosphate will 

 be found in the corpuscle fraction. By this method, the corpuscle fraction 

 was found to contain 3 per cent of the plasma. This value indicates the 

 upper limit of the amount of adhering plasma, since some of the ^^p 

 found in the corpuscle fraction may be due to a replacement of a part 

 of the non-labelled phosphate ions adsorbed on the surface of the cor- 

 puscles by labelled ions. 



That the line seen in Fig. 1 does not start at is due partly to the 

 presence of some plasma containing ^^p in the corpuscle fraction and 

 presumably partly to the presence of some labelled phosphate adsorbed 

 from the plasma by the surface of the corpuscles. In view of the very 

 extended corpuscle surface, it is conceivable that non-negligible amounts 



(1) 32p added to dogs blood kept at 37° was found to be almost equally distri- 

 buted after the lapse of 2 hours between plasma and corpuscles of equal weight. 



