Methods: Twenty patients (16 males, 4 females; mean ages 58.4±9.9 years; range 38 to 80 years) who underwent isolated coronary artery bypass graft (CABG) surgery between May 2008 and October 2008 were included in this study. Internal thoracic artery, saphenous vein, and radial artery grafts were harvested. Specimens were taken to laboratory in +4 ºC Krebs solution. Specimens were suspended in 10 ml organ bath containing Krebs solution.

Results: Amiodarone caused relaxation in all grafts (ITA, RA, SV) between 10-9-10-3,5 M concentration in a dose dependent manner (p<0.01). Maximum relaxation rates (mean) induced by amiodarone were 78.9%, 74.9% and 66.5% for ITA, RA and SV, respectively.

Conclusion: Although we did not evaluate the endotheliumindependent relaxation response in this study, higher rates of relaxation response were observed with ITA grafts comparing to other grafts, and these results were compatible with literature. According to the results of this study, amiodarone-class III antiarrhythmic agent- caused vasodilation in all three grafts in vitro. Vasodilator effect of amiodarone on grafts may help to increase patency rates.