Abstract: Objective To evaluate the effect of intraluminal injection of papaverine and nitroglycerin on endothelial function of the pedicle left internal mammary artery(LIMA) after preparation through organ bath.Methods The study comprised of 50 patients who underwent harvesting of the LIMA as a graft to the left anterior descending coronary artery in preparation for off-pump coronary bypass grafting. The LIMA was harvested by no-touch technique. The patients were randomly subdivided into two treatment groups and each had 25 patients. Three mg/3 mL heparinized autologous blood papaverine and nitroglycerin were intraluminally injected. The LIMA endothelium function was examined in isolated organ baths. Contractile function of arterial rings were obtained by using potassium (KCl 80 mmol/L) and three different concentration (10^-7 mol/L -10^-5 mol/L) of norepinephrine (NE) after intraluminal injection of these two vasodilators. Endothelium-dependent diastolic response was tested in response of 10^-7 mol/L -10^-5 mol/L acetylcholine (Ach).ResultsThe maximum contraction forces in response to 80 mmol/L KCl were not significantly different between papaverine and nitroglycerin (P=0.957); the relative vasoconstriction of papaverine and nitroglycerin after cumulative concentration of NE,10^-7mol/L (P=0.276), 10^-6 mol/L (P=0.396) and 10^-5 mol/L (P=0.554), they all showed no significant differences; endothelium dependent relaxation percentage with cumulative relaxation concentration Ach, 10^-7mol/L (P=0.299),10^-6 mol/L(P=0.163)and 10^-5 mol/L(P=0.089),was not significantly different. Conclusion The results suggest that IMA 3 mg/3 mL heparinized autologous blood papaverine and nitroglycerin as topical intraluminal vasodilators did not induce functional change of the artery.

Key words: coronary artery bypass grafting, internal mammary artery, organ bath, endothelial function, papaverine, nitroglycerin