The chloride channel blocker anthracene 9-carboxylate inhibits fatty acid incorporation into phospholipid in cultured human airway epithelial cells

Abstract

This study investigated whether making epithelial cell membranes impermeable to Cl- movement affects incorporation of fatty acids into membrane constituents. Epithelial cells were isolated from human nasal polyps, cultured for 5-7 days, and used to test the effect of anthracene 9-carboxylate (9-AC), known to inhibit Cl- conductance across the epithelial membrane, on the incorporation and desaturation of [I-14C]linoleic acid (C(18:2,n-6)) in experiments of up to 4 h duration. 9-AC (5 mM) reduced C(18:2,n-6) incorporation into phospholipid by 60-70%, and increased incorporation of C(18:2,n-6) into triacylglycerol by 50-100%. The decrease in C(18:2,n-6) incorporation into phospholipid was rapid and dependent on the concentration of 9-AC. Substitution of extracellular Cl- with gluconate significantly decreased C(18:2,n-6) incorporation into phospholipid, suggesting that the effect of 9-AC may occur by inhibiting Cl- conductance. Lipid analysis of cells exposed to 50μM-C(18:2) revealed that, as a consequence of the effect of 9-AC, the level of C(18:2,n-6) in cell membrane phospholipid was significantly lowered. The relative rate of C(18:2,n-6) desaturation was not apparently changed by 9-AC. These data suggest that Cl- conductance may play a role in fatty acid incorporation into epithelial cell membrane phospholipids.