EFFECT OF VITAMIN-E ON HUMAN GLUTATHIONE-PEROXIDASE (GSH-PX1) EXPRESSION IN CARDIOMYOCYTES

To determine the effect of vitamin E on cellular antioxidant enzymes, human ventricular cardiomyocytes were incubated with 200 mu M all-race mic-alpha-tocopheryl acetate for 14 d at pO(2)s of 150 and 30 mm Hg. C ellular Cu, Zn superoxide dismutase, catalase, and GSH-Px1 activities were measured. Although SOD and catalase activities were unaffected by a-tocopherol, GSH-Px1 activities increased (p < .0001) as much as two fold. This increase was independent of oxygen tension and selenium. Th e increase in GSH-Px1 activity became significant (p < .01) by day 4. A nonantioxidant analog of alpha-tocopherol, 200 mu M RRR-alpha-tocoph erol methyl ether, did not affect GSH-Px1 activities. Although GSH-Px1 mRNA levels mirrored the changes in enzyme activities, the de novo nu clear GSHPx1 transcript synthesis was unaffected by alpha-tocopherol. Because the increase in GSH-Px1 activities also occurred after cellula r alpha-tocopherol levels had plateaued, the above results were most c onsistent with posttranscriptional stabilization of GSH-Px1 mRNA by al pha-tocopherol or an alpha-tocopherol-related metabolic product.