It was investigated to clarify the relationship between the composition of the lipid fractions obtained from the ascitic fluid of Ehrlich ascites tumor bearing mice and its uncoupling activity after whole body irradiation (1,000 r). 1. Oxidative phosphorylation of Ehrllch ascites tumor cells was loosely uncoupled with the addition of ascitic lipid fraction extracted from tumor bearing mice.
2. The uncoupling activity of the lipid fraction on the oxidative phosphorylation of the tumor cells increased after whole body irradiation. 3. Ascitic lipid fraction, especially acetone soluble fraction accelerated mitochondrial swelling, and the swelling action was increased remarkably by the whole body irradiation. 4. No significant changes were observed in the proportion of acetone soluble fraction to acetone insoluble fraction in the ascitic lipid after X-irradiation, and the proportion of the both fractions was approximately 9 : 1, respectively. 5, Main compositions of total and non-esterified fatty acids in the ascitic fluid obtained from the control and X-irradiated groups were palmitic, stearic,
oleic, linoleic and palmitoleic acids, and the proportions of unsaturated acids, especially oleic and linoleic acids in both fatty acid fractions were greater in the X-irradiated group. 6. Remarkable increment of unsaturated fatty acid especially linoleic acid, was also observed in the total fatty acids of the tumor cells separated from
the X-irradiated group. 7. It can be concluded that an uncoupling agent extracted from ascitic fluid of the X-irradiated group was a mixture of long-chain fatty acids, especially oleic and linoleic acids. 8. It was also discussed that uncoupling oxidative phosphorylation in liver mitochondria after whole body irradiation may be caused by a similar mechanism to that in the turnor cells.</p
