Effects of transdermal nicotine treatment on structure and function of coronary artery bypass grafts

Smoking is a major risk factor for failure of coronary artery bypass grafts (CABG). Experiments were designed to determine effects of transdermal nico tine, independent of smoking, on structure and function of CABG. Saphenous veins were placed as CABG in untreated dogs (control) or in dogs treated wi th transdermal nicotine (one 11-mg or two 22-mg patches/day) for 5 wk. Seru m nicotine and plasma nitric oxide were measured. Grafts were removed and p repared for organ chamber studies and histology. Serum nicotine averaged 12 .1 and 118.7 ng/ml in the 11 mg/day and 44 mg/day groups, respectively. Pla sma nitric oxide was higher in dogs treated with 11 mg/day doses compared w ith controls. In organ chamber studies, endothelium-dependent relaxations t o thrombin and A-23187 and endothelium-independent relaxations to nitric ox ide were greatest in grafts from dogs treated with 11 mg/day doses. Intimal thickness of the grafts were similar among groups. However, staining for b one sialoprotein was increased in the media of grafts from the 11 mg/day tr eatment group. These data suggest that transdermal nicotine in doses compar able and double to those used for conventional smoking cessation treatment in humans does not adversely affect early patency of canine CABG up to 4 wk postoperatively. Transdermal nicotine, however, may increase production of and response to nitric oxide in bypass grafts.