382 ADVENTURES IN RADIOISOTOPE RESEARCH 



takes place cannot be disregarded. In view of the very low content of 

 organic acid soluble P compounds of the plasma, if a migration of such 

 compounds between corpuscles and plasma would take place, it should 

 be mainly directed from the corpuscles into the plasma. In view of 

 the fast rate of renewal going on in the corpuscles and the fast turnover 

 of the acid soluble P compounds in the plasma, the investigation of a 

 migration of organic acid soluble P molecules from the corpuscles into 

 the plasma or vice versa encounters difficulties. 



In the above connection it is of interest to remark that Solomon, 

 Hald and Peters^'^ found, in a recent investigation, that phosphate 

 esters present in the corpuscles are restrained from escaping by some 

 force in addition to the membrane of the corpuscles. The restraining 

 force is presumably a chemical aggregation or combination with sub- 

 stances of large molecular size. They arrived at the result mentioned 

 above by the following observation. When filtering blood which was 

 hemolysed by freezing, the ultrafiltrate obtained at 7° did not contain 

 any appreciable amount of organic P, while the opposite was the case 

 when saponin was used to obtain hemolysis. Frozen blood acts as much 

 as does intact blood so far as phosphates are concerned. The organic 

 esters remain intact as long as the blood is kept cold and their combi- 

 nation with substances of high molecular size remains unpaired. This is 

 not the case when saponin is added. Under the action of this agency the 

 binding forces break down, and the organic phosphate esters can enter 

 the ultrafiltrate. At 37° the phosphate esters can be ultrafiltrate d even 

 if the blood was hemolysed by freezing. In experiments in vitro with 

 intact blood at 37°, during 18 hours no appreciable amount of organic 

 phosphate ester was found to escape from the corpuscles into the plasma. 

 These results support the view that the P atoms present in the phosphate 

 ester molecules of the corpuscles reach the plasma, and vice versa, 

 after being converted into constituents of organic phosphate ions. 



As seen in Tables 8 a, b and c, with decreasing temperature the rate 

 of penetration of ^^P from the plasma into the corpuscles and also the 

 rate of its incorporation into organic P compounds strongly decreases. 

 While at 37°, in the course of 90 min, 22 per cent of the ^^P originally 

 present in the plasma diffused into the corpuscles, at 5° only 3.3 per 

 cent of the ^^P originally present in the plasma found their way into 

 the corpuscles. The comparison of the specific activity of the inorganic 

 P present in the corpuscles at 37° and 5°, respectively, leads to the 

 result that this activity is 37 times larger at 37° than at 5°. A similar 

 comparison of the specific activity of the organic P of the corpuscles 

 (exclusive the labile P of adenosintriphosphate) leads to a ratio of 80. 

 It is of interest to note that a decrease of the temperature hardly affects 



'^^F. C. Solomon, P. M. Hald and J. P. Peters, J. Biol. Chem. 132, 721 (1940). 



