Stable compounds of cigarette smoke induce endothelial superoxide anion production via NADPH oxidase activation

Objective - Endothelial dysfunction is an early manifestation of cigarette smoke ( CS) toxicity. We have previously demonstrated that CS impairs nitric oxide (NO)- mediated endothelial function via increased generation of superoxide anion (O-2(.-)). In these studies, we investigated whether stable compounds present in CS activate specific pathways responsible for the increased endothelial O-2(.-) production. Methods and Results - Short exposure of bovine pulmonary artery endothelial cells (BPAECs), human pulmonary artery endothelial cells, and rat pulmonary arteries to CS extracts (CSEs) resulted in a large increase in O-2(.-) production (20-fold, 3-fold, and 2-fold increase, respectively; P < 0.05 versus control), which was inhibited by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors diphenyleneiodinium, apocynin, and gp91 docking sequence-tat peptide but not by oxypurinol, the NO synthase inhibitor N-G-nitro-L-arginine methyl ester, or the mitochondrial respiration inhibitor rotenone. Exposure of BPAECs to acrolein, a stable thiol-reactive agent found in CS, increased O-2(.-) production 5-fold, which was prevented by prior inhibition of NADPH oxidase. Conclusions - These studies demonstrate that thiol-reactive stable compounds in CS can activate NADPH oxidase and increase endothelial O-2(.-) production, thereby reducing NO bioactivity and resulting in endothelial dysfunction. Clinically, these studies may contribute to the development of agents able to mitigate CS-mediated vascular toxicity.