Chronic Cigarette Smoke Exposure Impairs Vascular Endothelial Function With Reactive Oxygen Species Formation and Alterations in NO Synthase

A strong association between cigarette smoke exposure (CSE) and vascular endothelial dysfunction (VED) has been established; however, the precise mechanisms involved are not known. We observe that CSE impairs vascular endothelial function and induces cardiovascular changes in C57BL/6 male mice with reactive oxygen species (ROS)‐formation. Mice were exposed for periods of up to 48 weeks to cigarette smoke generated from 3R4F reference research cigarettes using the Teague TE‐10 smoking machine. CSE impaired acetylcholine (Ach)‐induced endothelial‐dependent relaxation of thoracic aorta segments. CSE also triggered persistent hypertension. Superoxide production in aortas of CSE‐mice was increased with coordinate overexpresion of NADPH oxidase subunits p22 phox and gp91 phox . Tetrahydrobiopterin (BH 4 ) was depleted in CSE‐mice but not in non‐exposed controls resulting in endothelial NO synthase (eNOS) uncoupling. Western blotting and immunohistochemistry showed a clear decrease in eNOS expression in aortas from CSE‐mice compared to controls. Phosphorylation of eNOS and Aktwas significantly decreased in response to CSE. Our data suggest that CSE‐induced ROS generation depletes BH 4 and impairs Akt‐mediated eNOS activation, resulting in VED and hypertension. Overall, our study provides important insights toward understanding how smoking contributes to the genesis of cardiovascular disease.