574 



ADVENTURES IX RADIOISOTOPE RESEARCH 



reinjected into the human subject under investigation. The labelled KCl was 

 previously carefully purified from radioactive impurities, especially from ^i^a. 

 Under the conditions prevailing in the Stockholm and Copenhagen cyclotrons, 

 where the KCl applied was bombarded with deuterons, the bombardment of 1 mgm 

 of sodium svipplies about 30 times as much ^^Na as *^K is formed by bombardment 

 of 1 mgm potassium. (Personal communication by Mr. K. Zerahn, to whom and 

 to Dr. Mel ANDEB we are much indebted for the purification of the active potassium 

 chloride samples.) The presence of minute amounts of sodium in the KCl sample 

 can thus become disturbing. The labelled KCl was added to blood in physiolo- 

 gical concentration thus as 1.1% solution. 



The blood samples, secured from the vena basilica at various intervals after 

 injecting a known aliquot of the activated blood were centrifuged, the corpuscles 

 washed with saline and their activity compared with that of a known aliquot 

 of the blood (corpuscles) injected. In our first experiments we compared the acti- 

 vity of dried corpuscle and plasma samples, but, in view of the fact that ^^K decays 

 with a half time of 12 his and the dr^•ing of the samples takes some time, we applied 

 later Zerahn's (1948) cuvettes in which the activity of fresh samples is measured. 

 These cuvettes weie also applied when determining the distribution coefficient 

 of *2K between plasma and red corpuscles in vitro. In these experiments to about 

 10 ml of freshly drawn heparinized blood kept at 37 °C, 0.1 ml of a physiological 

 sodium chloride solution containing about 0.05 mgm labelled KCl was added. After 

 the lapse of 15 minutes shaking was interrupted and the blood centrifuged in ice- 

 cold centrifuge tubes. Centrifugation is not to be prolonged, as corpuscles when 

 kept at a low temperature lose some of their potassium content. 



RESULTS 



In Fig. 1 the activity of 1 gm red corpuscles is plotted against time after 

 intravenous injection of labelled whole blood, while in Fig. 2 the results 

 of experiments are seen in which washed labelled red corpuscles were 

 injected intravenously. 



^300 

 ■^200 

 ° 100 



a. 

 V) 



Case 2. 



1 1 1 i 1 1 



10 20 30 40 50 60 

 Minutes after injection 



120 



Fig. 1. Change in the ^-K content of red corpuscles after injection 



of labelled whole blood. 



