Supplemental fatty acids alter lipid peroxidation and oxidant injury in endothelial cells

The purpose of this study was to determine the effects of supplemental fatty acids on oxidant injury in cultured endothelial cells. Porcine pulmonary artery endothelial cells (PAEC) in monolayer culture were incubated in culture medium supplemented with 0.1 mM fatty acid or with fatty acid vehicle alone for 3 h. Monolayers were then exposed to oxidant stress (100 microM H2O2 in buffer) or to control conditions (buffer alone) for 30 min. Supplementation with stearic acid (18:0) or oleic acid [18:1(n-9)] reduced H2O2-induced PAEC injury measured as release of intracellular lactate dehydrogenase (LDH). In contrast, supplementation with linolenic acid [18:3(n-6)] or eicosatrienoic acid [20:3(n-3)] enhanced H2O2-induced injury to PAEC. Both supplemental cis-vaccenic acid [18:1(n-7)] and 18:1(n-9) reduced the production of lipid peroxidation products in oxidant-stressed PAEC, whereas supplementation with 18:3(n-6) enhanced lipid peroxidation. Supplementation with 18:1(n-9) protected PAEC from H2O2 as long as 72 h after supplementation despite the intracellular redistribution of [18:1(n-9)] from triglycerides to phospholipids. Saturated and monounsaturated supplemental fatty acids protected PAEC from oxidant injury, but polyunsaturated fatty acids enhanced oxidant injury. These results support the hypothesis that supplemental fatty acids replace resident fatty acids, alter the oxidant reactivity of the cellular lipids, and thereby modify the oxidant susceptibility of PAEC.