RT Journal Article SR Electronic T1 Cigarette smoke exposure causes constriction of rat lung JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1095 OP 1099 DO 10.1183/09031936.99.14510959 VO 14 IS 5 A1 JL Wright A1 JP Sun A1 A Churg YR 1999 UL http://erj.ersjournals.com/content/14/5/1095.abstract AB Cigarette smoke is known to cause acute increases in airway resistance, but the mechanisms behind this effect are unknown. Lung explants were utilized to examine the constrictive effects of acute cigarette smoke exposure on bronchioles from rats in vitro that had or had not been previously exposed to cigarette smoke in vivo. It was found that smoke induced a small but consistent degree of contraction of the airways in vitro, which could be reduced by an endothelin receptor antagonist in the animals which had had no previous smoke exposure in vivo, and reduced by the oxidant scavengers superoxide dismutase or catalase in the animals with previous smoke exposure. In conclusion, cigarette smoke induces acute small airways constriction through both endothelin release and direct oxidant effects; which mechanisms are operative depends on the prior smoking status.