GLUTATHIONE-REDUCTASE ACTIVITY FOLLOWING RE-AERATION OF HYPOXICALLY PRETREATED WHEAT ROOTS

During the first 2 h of oxygen re-exposure, the GSH level was almost c onstant, while the GSSG increased about 10-fold. This results in a dec line of the GSH/GSSG ratio, which reflects oxidative stress induced by re-aeration following hypoxic pretreatment. Further evidence for this is an increase in lipid peroxidation measured as thiobarbituric acid- reactive material (TBA-rm) and the affected content of sulfydryl-group s in the root tissues. In spite of the high level of reduced glutathio ne in the roots under hypoxia-inducing conditions, they contained a re tarded glutathione reductase (GR) activity compared with aerobically g rown roots. Re-aeration up to 2 h resulted in a further decrease in GR activity. Only at the end of the 16-h period of re-aeration the enzym e activity was able to recover, by overshooting slightly those values of the continuously aerated controls. This was accompanied by a restor ing a high GSH/GSSG ratio and an enhanced level of GSH.