Fig. 2. Cellular reduced glutathione levels as a function of oxygen concentration and treatment with the conjugating agent CDNB. GSH levels in cells incubated for 15 min at 21, 5 or 1% O₂ in the presence or in the absence of 1 mm CDNB. Data are means ± S.E.M. of four independent experiments. ^*P<0.05 and ^**P<0.01.