Abstract: Aim Effects of estrogen on theproliferation of vascularsmooth muscle cells and theimpairment of endon thelium-d epentment vascularrela xation after vascular injury were studied.Methods Ovariectomized Wistar rats wererandomly dividedinto two subgroups treated with either 17βestradiol or vehicle and were subjected to balloon injury of theleft common carot id artery.Two weeks later, thedeg rees of myointimal thickening and proliferation of vascularsmooth muscle cells (VSMC)were evaluated by morphometric analysis and immunostained against proliferating cellular neuclear antigen (PCNA).Acety lcholine-induced endon thelium-depende ntrelax ation was measured.Results 17βestradiol signi ficantly inhibited theproliferation of VSMC (P<0.05)and attenuated neointimal area (P<0.05). Acety lcholine-induced endon thelium-dependentrelax ation was greatly reducedin injured arteries, with themax imal relax ation being 12 %±6 %.Estradiol ameliorated signif icantly theimpairment of vascularrelaxation, with themaximal relax ation being 48 %±9 %.Conclusion Estradiol can inhibitsmoo th muscle proliferation and ameliorate thedecrease in endon thelial-dependentrelax ation after balloon injury.

Key words: estrogen, endothelium