17β-estradiol effects on human coronaries and grafts employed in myocardial revascularization: a preliminary study

BACKGROUND This study was undertaken to compare the in vitro effects of 17beta-estradiol on human epicardial coronary arteries, resistance coronary arteries and on arterial vessels usually employed as grafts in surgical myocardial revascularization. METHODS Coronary artery rings (descending coronary artery, right coronary artery, circumflex coronary artery, first septal branch) and arterial graft rings (internal thoracic artery, gastro-epiploic artery) obtained from human heart donors with heart not suitable to cardiac transplantation were connected to force transducer for isometric force recording. Precontracted specimens with and without endothelium were exposed to increasing concentration of 17beta-estradiol (3-30-300-3000 nmol/l) and to vehicle (0.1% v/v ethanol). We also evaluated the effects of 17beta-estradiol on vessels before and 20 minutes after exposure to L-monomethyl-arginine and indomethacin. RESULTS 17beta-estradiol induced a significant relaxation in all precontracted vessels (mean maximum effect: 78,6% +/- 8,5). This effect was not different among the different rings and was not related to the presence of endothelium. N-monomethyl-L-arginine and indomethacin did not modify 17beta-estradiol relaxant effect. CONCLUSION The vasodilator action of the 17beta-estradiol is similar on coronary arteries, resistance coronary arteries and arterial vessels usually employed as grafts in myocardial revascularization.