Originally published in Arkiv for Kemi 3, 425 (1951). 



53. THORIUM B LABELLED RED CORPUSCLES 



G. Hevesy 



From the Institute for Research in Organic Chemistry, Stockholm 



The labelling of red corpuscles is an important application of radio- 

 active indicators as labelled erythrocytes are applied among others in 

 circulation studies and in the determination of blood corpuscle (blood) 

 volume^^). 



Labelling of red corpuscles with ^^P is made possible by the presence 

 of comparatively large amounts of labile acid soluble phosphorus in the 

 erythrocytes. Much of the ^^P which intrudes from the plasma into the 

 red corpuscles speedily participates in the glycolytic and other enzymatic 

 processes taking place in the erythrocytes. This participation involves 

 incorporation into labile organic phosphorus compounds and thus 

 "dilution" of the intruded ^sp. As a result of this "dilution" if in the 

 course of 1 hour 1 mgm intruding phosphorus carries 1 //curie into the 

 corpuscles 1 mgm phosphorus moving from such corpuscles in the opposite 

 direction carries into inactive plasma an appreciable smaller activity 

 which amounts to about ^12 or ^^ss of 1 //curie only. Interchange of phos- 

 phate between plasma and red corpuscles is a continuous process not 

 influenced by the presence of added labelled phosphate, the latter 

 having a negligible weight. Injected into the human circulation, such 

 labelled red corpuscles will lose 8 per cent or less of their activity in the 

 course of 1 hour. In the course of 20 minutes the loss is certainly less 

 than 3 per cent. This time interval is in most cases sufficient to carry out 

 circulation velocity or blood volume measurements. 



In a similar way, red corpuscles can be labelled by adding ^'-K to a 

 blood sample and shaking it in a thermostat for an hour or two^^^. In this 

 case — due to the much higher potassium content of the erythrocytes — 

 the intruded ^^K becomes "diluted" by endogenous potassium in a similar 

 way as intruded ^^P gets "diluted" by endogenous phosphorus and 

 correspondingly the ^^K labelled corpuscles injected into the circulation 

 lose less than 4 per cent of their activity in the course of 1 hour. 



^1^ cf. G. Nylin, Svenska Vetenskapsakad. Arkiv Kemi A 20, No. 17 (1945). 

 ^2^ G. Hevesy and G. Nylin, Acta Physiol. Scand. in print. 



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