THORIUM B LABELLED RED CORPUSCLES 535 



Comment to papers 51— 53 



In the first investigation (1939) on the labelling of red corpuscles with^^p^ labelled 

 sodium orthophosphate was added to rabbits blood (paper 49). The penetration 

 of 3-P into the red corpuscles was found to be a fairly slow process; most of the 

 penetrated ^^P was, however, found to be present very shortlj^ after penetration 

 in the labile acid soluble phosphorus fractions of the erythrocytes. This distribution 

 of the penetrated ^^F, in a pool of phosphorus compounds much larger than repre- 

 sented by the inorganic phosphate of corpuscles, make it possible to label red 

 corpuscles fairly stably and apply these tagged erythrocytes in blood csorpuscle 

 volume determinations. If after incubation for 1 — 2 hr the inorganic phosphate 

 of the red corpuscles alone took up substantial amounts of ^^P, after injecting 

 such a sample into an inactive circulation, the ^^p would soon be lost. As the con- 

 centration of inorganic phosphate in the red corpuscles is lower than in the plasma, 

 the exodus of ^^P would even take place in the inactive circulation at a more rapid 

 rate than its incorporation in the course of its in vitro incubation. The partici- 

 pation of a large labile, and to some extent of a non-labile acid-soluble pool of 

 phosphorus compounds in the uptake of ^^P, brings down the ^^P loss after injection 

 of the labelled erythrocytes into inactive circulation to from one-twentieth to 

 one-thirtieth of the loss which we would observe in the absence of such a pool. 

 Moie recent investigations by Goukley (1952) and by Gerlach (1954) lead to 

 the result that a part of the labelled acid-soluble phosphorus is already synthetized 

 under participation of plasma phosphate in the course of the entrance of ^^p 

 into the erythrocytes. 



One day after subcutanous injection of labelled phosphate to human subjects, 

 the acid-soluble phosphorus of the corpuscles was found to contain almost twice 

 as much ^^p than the plasma, while the plasma phosphatides contained only about 

 one-third and the red corpuscle phosphatides, which are renewed at a slow rate, 

 only about one-fortieth. These were the first experiments (1939) on the labelling of 

 human erythrocytes (paper 49). In mYro experiments in which human blood was 

 incubated with sodium phosphate containing ^^p were first carried out shortly 

 afterwards by Eisenman (1940). In the last mentioned experiments, a decrease of 

 the incorporation of ^sp into the red corpuscles with decreasing temperature 

 was observed. A very strong dependency of the rate of incorporation of ^^P into 

 the erythrocytes of the rabbit was later ascertained (paper 50), the energy of acti- 

 vation of this process being found as high as 15,000 cal. 



References 



A. I. Eisenman, L. Ott, P. K. Smith and A. Winkler (1940) J. Biol. Chem. 



135, 165. 

 E. Gerlach, A. Fleckenstein and K. J. Freundt (1954) Arch. Qes. Physiol. 



263, 682. 

 D. R. H. GouRLEY (1952) Arch. Biochem. Biophys. 40, 1. 



