NUCLEIC ACID IN THE CIKCl LATION 



765 



Table 5. — Percentage of the ^ap Content ok thk Liver Present as Acid- 

 soluble 32p 



of the total ^-P can be estimated to be present as phosphatide ^^p in 

 the liver. A non-negligible amount of ^^P will be also present as ribo- 

 nucleic acid formed in the course of the experiment, while the share of 

 32p incorporated into desoxyribosenucleic acid ^^P in the liver of full- 

 grown rats is very restricted. We must furthermore consider that a 

 considerable part of the ^^p split off from labelled nucleic acid in the 

 liver is carried into the circulation and from the plasma into the different 

 organs. 



The free liver phosphate interact with the free plasma phosphate at a 

 remarkable speed. Kalckar(^> and his associates record experiments 

 with rabbits taking 5 minutes only, in which after intravenous injection 

 of labelled phosphate the specific activity of the intracellular free liver 

 P varied between 8 and 37 per cent of the specific activity of the free 

 plasma P. 



Though the nucleic acid introduced into the circulation was free from 

 other labelled phosphorus compounds, at the end of the experiment the 

 specific activity of the free P of the plasma is showing a considerable 



Table 6. — Specific Activity of the Free Plasma P in Percentage of the 

 Activity of the Free Liver P at the End of the Experiment Taking 2 Hours 



percentage of the specific activity of the free P of the liver activity as 

 recorded in Table 6. 



In our experiments in which labelled sodium phosphate is ad- 

 ministered, after the lapse of 2 hours, the specific activity of the free 

 plasma P is somewhat higher than the specific activity of the free liver 

 P. In experiments in which the radiophosphate was administered by 

 subcutaneous injection to rats after the lapse of 2 hours an average 



^1^ H. M. Kalckar, J. Dehlinger and A. ^Iehler, J. Biol. Chem. 

 (1944). 



154, 275 



