Originally published in Arkiv for Kemi 23 A, 10 (1946). 



75. ATTEMPTS TO FIND PRODUCTS BLOCKING NUCLEIC 



ACID FORMATION IN THE CIRCULATION OF AN 



IRRADIATED ORGANISM 



L. Ahlstrom, H. Eulee, G. Hevesy, and K. Zerahn 

 From the Institute for Research in Organic Chemistry, Stockholm and Institute 



for Theoretical Physics, Copenhagen 



We communicated previously^ the results of some experiments which 

 demonstrate that beside blocking the formation of labelled desoxyribo 

 nucleic acid in irradiated Jensen sarcomata of the rat, a corresponding, 

 though less pronounced, effect is also observed when the sarcomata are 

 entirely shielded from the direct effect of the rays. By placing an ionisa- 

 tion chamber in the cavity of the shielded sarcoma the dose registered 

 amounted to 13 r only, while the second non-shielded sarcoma of the 

 same rat was exposed to a dose of 2000 r. The rate formation of labelled 

 nucleic acid was found to be diminished in both cases. 



In the above mentioned experiments the volume increment of both 

 the shielded and the irradiated sarcoma was determined as well. While in 

 the first days after irradiation about the same increment was observed 

 in both sarcomata, in the later phases of the experiment the volume 

 Increment of the irradiated sarcoma was found to be only 1/3 of that 

 shown by the shielded tumor. The effect of indirect irradiation on the 

 Jensen sarcoma is thus in the long run much less pronounced than the 

 effect of direct irradiation. 



The indirect action of Roentgen rays is possibly to be explained by a 

 transport of noxious substances formed under the action of radioation 

 from the place of formation by the circulation to the cells on which 

 they act upon. In the present note we describe some experiments which 

 were carried out in the hope to find in the circulation of irradiated 

 animals the presence of irradiation products which by blood transfusion 

 are carried over to a non-irradiated animal and act upon the mechanism 

 of nucleic acid formation in the tissues of the latter. 



^1^ L. Ahlstrom, H. EuLER and G. Hevesy, Ark. Kemi, A, 19 Nr. 13 (1945). 



