Nongenomic responses to 17β-estradiol in male rat mesenteric arteries abolish intrinsic gender differences in vascular responses

Abstract

1 The aim of the present study was to investigate the gender differences in the acute effects of 17β-estradiol on the rat superior mesenteric artery. 2 Isometric tension was measured in rings of mesenteric arteries from both male and female Sprague-Dawley rats. 3 Relaxation to acetylcholine was not significantly different between arteries (with endothelium) from male and female rats in the absence or presence of 17β-estradiol. After blockade of endothelium-dependent hyperpolarizations with apamin (0.3 μM) plus charybdotoxin (0.1 μM), acute exposure to 17β-estradiol (1 nM) for 30 min resulted in enhancement of relaxation to acetylcholine in arteries from male but not female rats. 4 After acute exposure to 17β-estradiol, mesenteric arteries from male rats were more sensitive to sodium nitroprusside than arteries from female rats. 5 Contractions of mesenteric arteries to phenylephrine and 9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F 2α (U46619) were greater in arteries from male rats than female rats. This difference was not detected after acute exposure to 17β-estradiol. 6 In preparations without endothelium, the enhancement of relaxation and reduction in contraction in arteries from male rats were preserved. 7 These results suggest that there exists a gender difference in the response to the acute nongenomic modulatory effect of 17β-estradiol in rat mesenteric arteries. Arteries from male rats seem to be more sensitive to the modulatory effects of 17β-estradiol than arteries from female rats. The effect appears to be mainly at the level of the vascular smooth muscles. © 2005 Nature Publishing Group. All rights reserved.