PRODUCTS BLOCKING NUCLEIC ACID FORMATION 



759 



EXPERIMENTAL 



In our early cxporinionts, we iriadiatod rats with Jensen sarcoma with 3000 r, 

 secured about 2 ml plasma or blood and injected the blood immediately into the 

 circulation of a non-irradiated rat. Labelled sodium phosphate was then admi- 

 nistered by subcutaneous injection, the rat killed after the lapse of 2 hours and 

 the specific activity of the dosoxyribo nucleic acid P and the free P extracted 

 from the sarcome, the liver, the kidneys and the intestinal mucosa was then deter- 

 mined. In view of the experimental difficulties encountered in these experiments 

 we investigated in our later sfudies the effect of Roentgen radiation on the rate of 

 renewal of desoxyribo nucleic acid in the liver, kidneys and intestinal mucosa 

 of the growing rabbit. 



As shown in an earlier investigation'^^ the rate of renewal of nucleic acid is 

 diminished under the effect of radiation in the normal organs as well. We carried 

 out experiments with about 4 weeks old rabbits, as in young animals the rate of 

 DNA formation is larger than in the fully grown rabbits. 



After the administration of a Roentgendosis, of 7500 to 10,000 r, we have secun-d 

 10 — 25 ml blood from the irradiated rabbit and injected it into the veins of a 



Table 1. — Rate or Formation of Desoxyribo Nucleic Acid in the Organs 

 OF Rabbits Weighing ca 560 gm after Transfusion of Irradiated kesp. Non- 

 Irradiated Blood of a Sister-RabB'It. Time of the Experiment = 2 Hours 



Non-irradiated 

 0.39 i 0.20 I 3.0 I 0.32 ] 0.21 ; 2.6 

 Mean value ! Irradiated 



(l 0.41 I 0.13 I 3.0 I 0.22 | 0.13 | 2.5 

 Percentage difference between the value obtained after 

 transfusion of non-" irradiated and irradiated blood 

 I 5 I 35 I I 30 1 39 | 



^1^ L. Ahlstrom, H. Euler and G. Hevesy, Ark. Kemi A 19, Nr. 9 (1944). 



