Alterations in the Oxidative Metabolism of Rats with Induced Tolerance: in Vitro Study of Diaphragm

Oxidative metabolism of diaphragms from endotoxin- and trauma-tolerant rats was investigated, utilizing the reduction of tetrazolium salt. It was found that diaphragms from normal and stress-tolerant animals did not differ in "oxidative performance" (activity in the absence of the redox dye phenazine methosulfate). However, diaphragms from tolerant animals exhibited a highly significant enhancement in "oxidative potential" (activity in the presence of phenazine methosulfate). This change was apparently not precipitated by adjustments in circulatory dynamics, nor was it related to reticuloendothelial stimulation. The suggestion is made that the effects observed may develop through the secondary release of endogenous epinephrine. Evidence is presented suggesting that the enhancement of "oxidative potential" exhibited by the parenchymal tissues of tolerant animals represents an adaptation in metabolism whereby pools of potentially oxidizable foodstuffs are stockpiled.