Endothelium-dependent relaxations produced by acetylcholine in mesenteric arteries of C57 and ApoE mice 30 days after ovariectomy (OVX) or sham surgery (Sham). Responses are expressed as the percentage of relaxations relative to the NE-induced precontractions. A: comparison between C57 Sham and ApoE Sham. B: comparison between C57 OVX and ApoE OVX. C and D: effects of ovariectomy on acetylcholine-induced vasorelaxation in C57 and ApoE mice, respectively. Data are reported as means ± SEM (n = 8 to 10 per group). *P < 0.05, **P < 0.01 vs respective control (ANOVA).