Effect of cigarette smoke on endothelial regeneration in vivo and nitric oxide levels

Background. Cigarette smoking accelerates atherosclerosis and restenosis af ter vascular reconstruction. The mechanisms by which smoking alters vessel structure after injury are unclear. This study examined the effects of ciga rette smoking on endothelial regeneration, an important component of arteri al remodeling. Materials and methods. Adult male rats were subjected to balloon injury of the thoracic aorta and exposed to mainstream cigarette smoke via a Griffith -type smoking machine for 2 weeks. Control groups included rats which were restrained in the machine but not smoked and a group not utilizing the mach ine. Aortic reendothelialization was determined using Evan's blue staining of the arterial surface. Serum levels of nitric oxide were measured to dete rmine if smoke exposure altered this potential endothelial cell mitogen. Results. Cigarette smoking increased aortic endothelial regeneration (78.4 +/- 4.6% vs 59.2 +/- 2.1%, P < 0.05) and was associated with an increase in serum nitric oxide level (59.9 +/- 7.1 mu M vs 28.5 +/- 1.8 mu M, P < 0.05 ). Daily restraint alone in the smoking machine had no effect on endothelia l regeneration. Conclusions. This is the first report on the effects of smoking on endothel ial regeneration and demonstrates that smoking increases reendothelializati on after large vessel injury and serum levels of nitric oxide, an EC mitoge n. (C) 1999 Academic Press.