EXOGENOUS FATTY-ACIDS MODULATE THE FUNCTIONAL AND CYTOTOXIC RESPONSESOF CULTURED PULMONARY-ARTERY ENDOTHELIAL-CELLS TO OXIDANT STRESS

We previously reported that supplementation with exogenous fatty acids modulated the susceptibility of cultured pulmonary artery endothelial cells (PAEC) to oxidant-mediated cytotoxicity, The current study inve stigates the effects of fatty acids with increasing degrees of unsatur ation on oxidant-mediated dysfunction and cytotoxicity in cultured por cine pulmonary artery and aortic endothelial cells (AEC). Monolayers s upplemented with 0.1 mmol/L oleic (18:1), linoleic (18:2), or gamma-li nolenic (18:3) acids were exposed to oxidant stress (100 mu mol/L hydr ogen peroxide (H2O2)) or to control conditions for 30 minutes. Gas chr omatographic analysis of the PAEC fatty acids confirmed incorporation of supplemental fatty acids into PAEC lipids. Cytotoxicity, measured a s the release of intracellular lactate dehydrogenase (LDH), and PAEC m onolayer barrier function, assessed by measuring the monolayer clearan ce of Evans blue dye bound to albumin, were determined for 1 to 3 hour s after oxidant stress. The PAEC and AEC demonstrated comparable respo nses to H2O2. Hydrogen peroxide caused increases in monolayer permeabi lity and detachment of cells from the monolayer that were most attenua ted by supplementation with 18:2 or 18:3, and to a lesser degree with 18:1. In contrast, H2O2-mediated LDH release was attenuated by supplem entation with 18:1, whereas 18:2 and 18:3 potentiated cytotoxicity aft er exposure to H2O2. These results indicate that the relationship betw een PAEC lipid composition and oxidant susceptibility is complex and t hat the extent of fatty acid unsaturation does not predict the functio nal or cytotoxic responses of PAEC to oxidant stress. Furthermore, the se results suggest that functional derangements may not correlate with traditional assays of cytotoxicity induced by oxidant injury in cultu red endothelium.