Influence of X-Ray on Oxygen Consumption of Spleen and Thymus Glands of Rats

Abstract

Previous investigations have indicated that the oxidative phase of intermediary carbohydrate metabolism in hematopoietic tissues is inhibited by whole-body X-irradiation. DuBois et al. (1) found that citric acid synthesis in vivo is markedly depressed in the spleens and thymus glands after lethal and sublethal doses of X-ray. A depression of oxygen consumption by slices of a variety of tissues from irradiated animals has been reported, and this metabolic defect has been attributed to inhibition of sulfhydryl enzymes (2). However, several recent studies involving assays for specific enzymes (3-7) and measurements of the respiration of tissue slices (8) do not support the idea that inhibition of the oxidative phase of carbohydrate metabolism is a general occurrence in the tissues of irradiated animals or that sulfhydryl enzymes are especially susceptible to inhibition by ionizing radiations in vivo. The findings of various investigators on this subject have been reviewed recently by DuBois and Petersen (9). The present study was undertaken to obtain further information on the influence of radiation on the oxidative capacity of hematopoietic tissues. Measurements of endogenous respiration and the oxidation of several intermediates of the tricarboxylic acid cycle were made on the spleens and thymus glands of irradiated rats. The results of this study indicate that radiation produces a marked decrease in endogenous respiration of the spleen and thymus glands. This effect on oxygen consumption of the irradiated spleen is reduced by pretreatment of animals with p-aminopropiophenone (10) or cysteine (11).