Abstract: To determine the effects and mechanism(s) of genistein on endothelial functions, the model of mesenteric-chamber with intravital fluorescence videomicroscopy and image analysis were used. After preconstriction with norepinephrine (NE; 10−6 M), vascular responses to different doses of genistein (10−2–10−7 M) were recorded with real time video-camera. The mechanism(s) of vasodilation was also determined by using Nω-L-arginine methyl ester (L-NAME; 100 μM), the inhibitor of nitric oxide synthase (NOS inhibitor), and/or indomethacin (INDO; 10 μM), cyclooxygenase inhibitor. The results indicated that the topical application of 10−2–10−7 M genistein on mesenteric microvessels caused the increase in arteriolar diameters from 33% to 48%, respectively. The effects of genistein on mesenteric endothelial-dependent vasodilatation could be mediated through both L-arginine/NO and cyclooxygenase pathways. Our finding indicated that genistein could induce endothelial-dependent vasodilation similar to 17β-estradiol.
