Effects of dietary factors on antioxidant enzymes in rats exposed to hyperbaric oxygen.

To delineate the effect of dietary supplementation with vitamin E (Vit E) alone or in combination with riboflavin (Rib) or selenium (Se) or both, on biological oxidative damage in rat brain and lungs we exposed rats to hyperbaric oxygen (HBO) and measured the activities of glutathione reductase (GSSG-R), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and glucose-6-phosphate dehydrogenase (G-6-PD) prior to or 48 h after exposure. Rats fed the dietary supplements, and a control group maintained on an unsupplemented diet, for 30 d, were each divided into 2 subgroups, of which 1 was exposed to 4.5 absolute atmospheres (ATA) of 100% oxygen for 30 min, hereafter referred to as "exposed". The remaining subgroups were left unexposed. Pre-exposure GSSG-R activity in brain was elevated in all experimentally fed groups (ranging from 23 to 84%) compared with the unexposed control, whereas GSH-Px, G-6-PD and SOD activities were unchanged. The lungs showed significant increases in pre-exposure GSSG-R, ranging from 15 to 28%, and GSH-Px, ranging from 13 to 23%, activities in all the groups fed the supplemental nutrients, except those on Vit E alone. Increases in G-6-PD activity were observed only in those fed supplements of Rib. In most cases exposure to oxygen caused an increase in GSSG-R, GSH-Px and G-6-PD activities. However the increases were higher in the supplemented groups.(ABSTRACT TRUNCATED AT 250 WORDS)