N-acetylcysteine prevents cigarette smoke induced small airways alterations in rats

This study investigated the effect of cigarette smoke exposure and the potential protection N-acetylcysteine (NAC) in rat lungs. Forty-eight rats were exposed to cigarette smoke (CS) for 10 weeks, without (CS group) or with (CS+NAC group) oral intake of NAC 200 mg x rat(-1) x day(-1), or to fresh air (Control). All rat lungs were assessed in terms of lung function, ventilation distribution (nitrogen, helium and sulphur hexafluoride phase III slopes), and morphometry (airway wall thickening of small, medium and large bronchi). The small bronchi, defined as the airways with an internal perimeter <1,000 microm showed significantly thicker airway walls in the CS than in the Control group. By contrast, no airway wall thickening was observed in the CS+NAC group with respect to Control. Except for decreased lung volumes and compliance in CS and CS+NAC groups, which were entirely attributable to smaller body weight gain, lung function was indistinguishable from Control. Phase III slopes were significantly increased only in the CS group. In conclusion, smoke-induced alterations in the rat lungs were reflected in wall thickening of the small bronchi and increased ventilation maldistribution. These smoke-induced morphometric and ventilation distribution alterations were prevented by N-acetylcysteine.