340 ADVEXTURES IX RADIOISOTOPE RESEARCH 



Table 29. — Specific Activity of P Fractions 



IN THE Organs of a Hen Weighing 900 gm 

 Labelled phosphate was administered to a laying hen 

 by subcutaneous injection at the start of the expe- 

 riment; the hen was killed 5 hours later 



Fraction 



Relative speciiic 

 activity 



Plasma lecithin P 



Plasma cephalin P 



Liver lecitliin P 



Liver cephalin P 



Liver spliingomyelin P 



Liver protein P 



Kidney lecithin P 



Kidney cephalin P 



Intestinal mucosa lecithin P .... 

 Intestinal mucosa cephalin P . . . . 

 Intestinal mucosa sphingomyelin P 



1.00 

 0.98 

 2.76 

 2.93 

 1.38 

 0.15 

 L15 

 1.69 

 0.90 

 1.05 

 1.10 



It is, therefore, not surprising that the fractions obtained from the 

 lien's liver are similar to those secured from the rabbit's liver in experi- 

 ments of much longer duration. In the kidneys of the laying hen the 

 phosphatide molecules are renewed at a slower rate than in the liver 

 and, in this organ, as was to be expected, cephalin is found to be mark- 

 edly more active than lecithin. 



The liver sphingomyelin of the laying hen which does not enter the 

 yolk to any appreciable extent is renewed at a decidedly lower rate 

 than the petrol-ether soluble phosphatides. It is also interesting to note 

 that the rate of rejuvenation of the protein P in the liver of the laying 

 hen is about 20 times slower than that of the phosphatide P. 



In the intestinal mucosa, cephalin and sphingomyelin are formed at a 

 somewhat higher rate than lecithin. In the kidneys cephalin was found 

 more active than lecithin. That the rate of renewal of phosphatides 

 in the liver of laying hens is decidedly higher than in the intestinal 

 mucosa or other organs was also found in our earlier researches. (i) 



Experiment with perfused cat liver 



The experiment on cat liver which was carried out with the kind help 

 of Professor Lundsgaard also indicates the faster cephalin turnover 

 in experiments of short duration. The fasting cat used in this experiment 

 weighed 3.3 kgm. Blood circulated for 70 min through the isolated livcM-. 



1 G. Hevesy and L. Hahn, Kgl. Danske Vidensk- Selskab, Biol. Mcdd. 14, 

 2 (1938). 



