SELENIUM ENHANCES GLUTATHIONE-PEROXIDASE ACTIVITY AND PROSTACYCLIN RELEASE IN CULTURED HUMAN ENDOTHELIAL-CELLS - CONCURRENT EFFECTS ON MESSENGER-RNA LEVELS

Selenium (Se) is an essential component of glutathione peroxidase (GSH -Px), an enzyme that protects cells by reducing intracellular peroxide s. Impaired Se status and GSH-Px activity seem associated with increas ed risk of atherosclerotic vascular diseases. This study reports the e ffects of Se supplementation on GSH-Px activity, on prostacyclin (PGI( 2)) production, on 12-hydroxy-eicosatetraenoic acid (12-HETE) levels, and on GSH-Px mRNA expression in cultured human umbilical vein endothe lial cells (HUVEC). Se-enriched HUVEC showed significant increase of b oth GSH-Px activity and thrombin-stimulated production of PGI(2) in th e presence of stable concentrations of 12-HETE. On the other hand, an inverse correlation between Se concentrations in culture media and GSH -Px mRNA levels in Northern blot analysis was shown; this suggests tha t a major degree of regulation for GSH-Px expression by Se is most lik ely exerted at the posttranscriptional level. These observations may h elp to explain the increased incidence of atherosclerosis described in Se-deficient individuals.