Experimental Study On Vein Grafts Function Preserved By ET-receptor Antagonist (BOSENTAN)

Objective: Endothelial dysfunction, specifically endothelium-derived contracting factors have been implicated in the development of vessel grafts vasospasm. The potent vasoconstrictor endothelin-1 (ET-1) has received much attention in this regard. The present study was designed to evaluate the effects of ET-receptor antagonist (Bosentan) on endothelial function of the vein grafts.Part I Method: Vascular segments of saphenous vein were obtained from 19 cases undergoing elective coronary artery bypass graft (CABG) and in vitro endothelium-dependant and -independent responses to Acetylcholine (Ach) and Sodium Nitroprusside (SNP) were assessed. Isometric dose response curves (DRC) to Ach and SNP were constructed in pre-contracted rings in the presence and absence of Bosentan (3 μm/L) using the isolated organ bath apparatus. Percent maximum relaxation (%E_max) and sensitivity (PEC50) were compared between interventions. Results: Ach caused dose-dependent endothelium-mediated relaxation in saphenous vein. In the presence of Bosentan, Ach-induced relaxation was significantly augmented (%E_max Bosentan 58.17± 4 vs control 35.29 ± 3 P<0.05). The effects of these...