OLEIC-ACID SUPPLEMENTATION REDUCES OXIDANT-MEDIATED DYSFUNCTION OF CULTURED PORCINE PULMONARY-ARTERY ENDOTHELIAL-CELLS

We have previously shown that supplementing cultured porcine pulmonary artery endothelial cells (PAEC) with exogenous oleic acid (1 8:1 omeg a9) alters the fatty acid composition of the cells and reduces oxidant -mediated cytotoxicity. Because the mechanisms by which lipid alterati ons modulate oxidant susceptibility have not been defined, the ability of 18:1 to reduce hydrogen peroxide (H2O2)-mediated PAEC dysfunction was evaluated. PAEC monolayers on polycarbonate filters were incubated for 3 h in maintenance medium supplemented with either 0.1 mM 18.1 in ethanol vehicle (ETOH) or with an equivalent volume of vehicle alone. Twenty-four hours later monolayers were treated for 30 min with 50 or 100 muM H2O2 in Hanks' balanced salt solution (HBSS) or with HBSS alo ne (nonoxidant control). As a functional index of PAEC monolayer integ rity, the permeability of monolayers to albumin was then measured for 3 h. Treatment with 100 muM H2O2 caused cytotoxicity and progressive i ncreases in PAEC monolayer permeability that were attenuated by 18:1 s upplementation, whereas 50 muM H2O2 caused only a transient increase i n permeability without cytotoxicity. Supplementation with 18:1 also at tenuated H2O2-induced reductions in PAEC adenosine triphosphate (ATP) content and disruption of PAEC microfilament architecture. The ATP con tent of PAEC monolayers was reversibly reduced in the absence of oxida nt stress by incubation with glucose-depleted medium containing deoxyg lucose and antimycin A. Metabolic inhibitor-induced ATP depletion incr eased monolayer permeability and altered cytoskeletal architecture, al terations that resolved during recovery of PAEC ATP content. These res ults demonstrate that ATP depletion plays a critical role in barrier d ysfunction and suggests that the ability of 18:1 to reduce oxidant-med iated PAEC dysfunction and injury may relate directly to its ability t o preserve PAEC ATP content. (C) 1993 Wiley-Liss, Inc.