Effects of Free Fatty Acids on Glutathione Redox Status in Cultured Endothelial Cells

Park, Joong Yeol; Kim, Chul Hee; Chung, Yun Ey; Kim, Hong Kyu; Kim, Young Il; Hong, Sung Kwan; Lee, Jae Dam; Lee, Ki Up

Abstract

BACKGROUND: Although plasma free fatty acids (FFA) are frequently elevated in diabetes mellitus, its role in the pathogenesis of diabetic vascular complications has not been well investigated. Recent stuclies reported that FFA may cause endothelial dysfunction through an enhancement of oxidative damage by decreasing glutathione redox cycle, an important anti-oxidant defense system in endothelial cells. In this study, we examined the effects of increased availability of FFA on intracellular glutathione redox cycle. METHODS: Bovine pulonary endothelial cells were exposed to 90 umol/L linoleic acid with or without 0.1 mM 2-bromopalmitate, an inhibitor of mitochondrial fatty acid oxidation, for 6hr. Components of the glutathione redox cycle such as total glutathione, reduced glutathione(GSH) and oxidized glutathione(GSSG) concentrations were measured by HPLC. RESULTS: Total glutathione concentration in cultured endothelial cells exposed to linoleic acid was significantly lower than that in control cells (10.8+ 0.5 vs 14.1+0.8 umol/g protein, P<0.05). Linoleic acid significantly decreased GSH concentrations (10.5+0.4 vs. 13.8+0.5 pmol/g protein, P<0.05) and the ratio of GSH/GSSG(26.3+1.3 vs. 47.0+2,1, P<0.05). Compared to cells exposed linoleic acid alone, total glutathione(13.5+0.5umol/g protein, P<0.05) and GSH concentration(13.2+0.4 pmol/g protein, P<0.05) significantly increased in cells treated with 2-bromopalmitate and linoleic acid. The ratio of GSH/GSSG in cells treated with 2-bromopalmitate and linoleic acid was higher th.an that in cells exposed to linoleic acid alone(44.1+1.3, P<0.05). CONCLUSION: Increased provision of FFA resulted in a derangement of glutathione redox cycle in cultured endothelial cells, which appears to be related to an increase in mitochondrial FFA oxidation. These results suggested that FFA can increase the risk of diabetic vascular complications.