CHANGES IN LIPIDS OF CELLULAR MICROSTRUCTURES IT)! 



But the mechanisms underlying this clianf^e in the eells of these twt) tissues may 

 be different. As for radiation induced cliaiiires of the Hpid metaboUsni in Hver, I 

 have worked a httle in this field, and we are well aware of the fact that in this 

 case an hnportant role could be jilayed not by a direct effect of radiation ou the 

 organ, but by an indii-i'ct one. Changes of the lipid metabolism in ihe liver uiay 

 be ascriloed in particular to an increased cortisone secretion found following 

 irradiation. Cortisone is capable of stimulating lipid deposition. I do not know 

 how cortisone would effect different lipid fractions, but its administration raises 

 the total lipid content. The process occurs as a rapid and sharp I'eaction. 



DOEMiN : I would hardly be able to give the answers your remarks call for. Indeed 

 they amount to a question about the causes of the changes we have rei:)orted. 

 Up to the present this has not been the purpose of our investigations. Before 

 starting to decipher the mechanisms involved we thought it necessary to gather 

 some pertinent facts, to find out what is changing and how it is changing. 



Of coiu-se we realize all the differences there are between liver and intestinal 

 mucosa both in cellular composition, and in biochemical peculiarities, as well as 

 the differences of their reactions to radiation. I agree with you that these 

 differences are great indeed. Precisely because of that we have chosen these organs 

 for comparison. And now there arises the problem of elucidating the factors that 

 induce the changes we have established as specific for this or that organ. 



In future work biochemical changes in diverse areas of the tissue will be 

 evaluated differentially and compared with the histological picture. 



I quite agree with you that on the one hand, metabolic disturbances in certain 

 tissues of the irradiated organism may be an indirect effect of some distant in- 

 fluences (for example hormonal) while on the other hand, the mechanism of the 

 disturbances in the lipid metabolism of the liver following irradiation (among 

 others an increase in the total lipid content) may be quite different from that 

 operating for the intestinal mucosa. Lipid accumulation in the liver may be a 

 result of neogenesis or deposition from the blood, or both. As was shown also 

 in our laboratoryt in experiments on angiostomized dogs with canulated hepatic 

 and portal veins, the intestines in fasting animals following irradiation were in 

 most cases enriching the blood witli lipids in spite of hyperlipemia (under normal 

 conditions the reverse was true). At the same time the liver was releasing the 

 lipids into the blood stream in a smaller quantity than usual, or was even taking 

 it up. These phenomena have been registered already within 2 hr of irradiation. 

 It is possible that some of the changes in the content of certain lipid fractions of 

 the liver cell components reported to-day, are related to this "pumping over" of 

 the lipids into the liver from other abdominal organs. 



During the studies of different asjtjects of the acetylcholine metabolism in the 

 body following irradiation, it was shown in our laboratory^ that immediately 

 after the radiation exposure begins a transport of considerable amount of 

 acetylcholine into the liver by the jDortal blood. This persists throughout the 

 j)eriod of the acute radiation sickness. At the same time it is known§ that acetyl- 

 choline can activate phospholipid metabolism. Activation of the metabolism of 



fDoEMiN, N. N. (1960). In "Voprosy radiobiologii". Vol. Ill, p. 158. Leningrad; 

 Smirnov, K. v., and Shaternikov, V. A. (190(J), Vojir. med. Khim. 6, 464. 



X Smirnova, K. V. and Shaternikov, V. A. (1960). C.R. Acad. Sci. U.R.S.S. 131, 961. 



§ HoKiN, L. E. and Hokin, M. R. (19.55). Biochim. Biophijs. Acta 16, 229; (1959). 

 J. Biol. Chem. 234, 1387; and other papers by the same authors. 



