Oxidative Swelling and Phosphorylation in Rat Liver Mitochondria: Combined Effects of Linoleate, Starvation, Glucose and X Irradiation.
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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The objective of this study was to determine the effects of whole-body x irradiation on structural and functional integrity of rat liver mitochondria. The investigation was designed to approach the objective by intercomparing effects of a ethyl linoleate in the diet, b starvation, c intraperitoneal glucose, and d whole-body x irradiation on oxidative swelling and oxidative phosphorylation. Iron-induced mitochondrial swelling associated with lipid oxidation was used as an index of injury to the structural integrity of the outer membrances. Oxidative phosphorylation with succinate as substrate was selected as an index of the functional integrity of the inner membranes. In rats exposed to 1000 R, the lag time for oxidative swelling was found to be decreased below that for controls 24 hours postexposure and the efficiency of oxidative phosphorylation was increased above the controls. In comparing diets, results with rats fed a fat-free diet indicated that the lag times for the oxidative swelling were increased above those for rats fed a diet supplemented with 5 percent ethyl linoleate, whereas the efficiency of oxidative phosphorylation was lower for the fat-free group than for the supplemented one. More malondialdehyde was formed in mitochondria from x irradiated rats fed a fat-free diet than in unirradiated control at a comparable time during oxidative swelling. Shorter lag times for oxidative swelling and lower oxidative phosphorylation values were observed for starved rats than for fed rats. The results support the conclusion that whole-body x irradiation induces a structural alteration of outer membranes and a functional enhancement in mitochondria. Author