Oxygen-induced inhibition of mouse brain lactate dehydrogenase

The lactate dehydrogenase (LDH) activity of mouse brain homogenates was examined after exposure to hyperbaric oxygen (5763.8 mm Hg Po2) and compared to room air controls (158.8 mm Hg Po2). The effect of reduced glutathione on LDH activity after hyperbaric oxygen exposure was also examined. The activity of LDH after treatment with hyperbaric oxygen was significantly diminished when compared with controls. In the presence of reduced glutathione, homogenates exposed to hyperbaric oxygen demonstrated higher activity than did homogenates incubated without glutathione. It is concluded that oxygen-induced inhibition occurs through the oxidation of essential free sulfhydryl groups and that this oxidation can either be prevented by reduced glutathione or the disulfide bridges may be reduced to free sulfhydryl groups by the glutathione after oxidation.