762 ADVBXrURES IX RADIOISOTOPE RESEARCH 



iidenosiiitilphosphate containing labelled labile P introduced into the 

 circulation, to behave almost as injected labelled phosphate. Marshak 

 and Walker(^) who investigated the uptake of ^sp by the nuclei 

 of the liver tissue, found the same percentage uptake after intravenous 

 injection of labelled sodiumphosphate and that of labelled adenosintri- 

 phosphate. 



Labelled phosphoiylcholine administered by intraperitoneal injection 

 to rats was found to split off at a rapid rate phosphate^^^ In their study 

 of the metabolism of labelled aminoethylphosphoric acid Chargaff and 

 Keston^^^ arrive to the conclusion that an enzymic hydrolysis of amino- 

 ethylphosphoric acid takes place in the tissues. 



That labelled plasma phosphatides introduced into the circulation 

 are not decomposed, resp. are decomposed at a slow rate only, is due to 

 the fact that these are normal components of the plasma, which inter- 

 <'hange as such with the tissue phosphatides.^*^ 



This note contains the results of an investigation of the fate of labelled 

 nucleic acid introduced in the circulation of the rat. 



EXPERIMENTAL 



To 3 Jensen sarcoma rats together 0.8 milliCurie ^^P was administered by sub- 

 •cutaneous injection. After the lapse of 5 days the desoxyribonucleic acid was 

 •extracted separately from the pooled livers and the pooled sarcomata. The nucleic 

 acid was purified as described previously^*\ The purification method supplies 

 nucleic acid free from all other phosphorus compounds but its yield is restricted, 

 18 mgm liver nucleic acid and 196 mgm sarcoma nucleic acid being obtained, 

 Tiaving a total activity of 4 microCuries. The average molecular weight of the 

 in the course of the purification process depolymerized nucleic acid was found 

 to be 14,000. 



5 mgm of liver nucleic acid in the first, 5 mgm sarcoma nucleic acid in the 1 1 

 following experiments, dissolved in 0.5 cc. physiological sodiumchloride solution 

 were injected in the circulation of the rat. After the lapse of 2 hours the rat was 

 iilled, the specific activity of the plasma, the total activity of the blood (or 

 plasma), the total and specific activity of the free P, acide soluble P and total 

 P of the liver and the total activity of other organs was determined as well. 



^i) A. Marshak and A. C. Walker, Amer. J. Physiol. 143, 235 (1945). 



^2)r. F. Rilby, J. Biol. Chem. 153, 535 (1944). 



<3) E. Chargaff and A. S. Keston, J. biol. Chem. 134, 515 (1940). 



(^> G. Hevesy and L. Hahn, Kgl. Danske Vidensk.Selsk. Biol. Medd., 15, Nr. 6 

 (1940); S. L. ZiLVERSMiT, G. Enteman and M. C. Fischler, J. Gen. Physiol. 

 26, 333 (1942/43); cf. even F. L. Haven and W. F. Bale, J. Biol. Chem. 129, 

 23 (1939). 



f (s^ H. EuLER and G. Hevesy, Kgl. Dansk. Vidensk. Selsk. Biol. Medd. 17, No. 

 8 (1942). 



