432 



ADVENTURES IN RADIOISOTOPE RESEARCH 



Table 5. — Rate of Disappearance of ^^'^P from the Circv- 

 LATiON OF Rabbits Weighing 2.1 and 2.7 kgm., Respectively 



Time in miu 



i'ei-cent of ^•^I' injected present 

 in 1 trin i)liisma 



Diluting fluid volun e 



in cc. (apparent 



extracellular 



volume) 



in percent of 

 body weight 



When investigating the staining capacity of dyes it was found that 

 generally the rate of coloration increases with decreasing diffusion rate 

 in water (Rous et al. 1930 ; Smith and Rous 1931 ; Menkin and 

 Menkin 1930). From the capillaries of the frogs mesentery trypan blue 

 was found to disappear exponentially with a half-time period of 2 min 

 (Menkin and Menkin 1939). 



We have not yet mentioned the fact that an outlet of the plasma 

 24Na, for example, is given by intrusion into the corpuscles. This outlet 

 is a very restricted one. We found the 24Na content of 1 gm corpuscles 

 of the rabbit to be, after the lapse of two hours, 11 percent of that 

 of 1 gm plasma. From this figure and the haematocrit value (34 percent) 

 of rabbit blood it follows that, expressed in diluting body fluid volume, 

 the uptake of ^^Na by the corpuscles corresponds to somewhat less than 

 4 cc, while the total diluting volume of a rabbit weighing 2,5 kgm makes 

 out as much as about 700 cc. After the lapse of P/s hours, the ^^K con- 

 tent of 1 gm corpuscles was found to be 40 percent of that of 1 gm 

 plasma and the ^sp content 48 percent. These figures correspond to an 

 additional diluting volume of 14 and 16 cc, respectively. The water 

 content of the corpuscles of the rabbit being about 63 percent, the 

 role of the corpuscles as additional outlet of the labelled water mole- 

 cules introduced into the plasma is not quite insignificant. 



