Relaxant effects of 17β-estradiol in the rat tail artery are greater in females than males

To investigate whether sex differences contribute to the variability reported for acute effects of 17β-estradiol on vascular reactivity, the response to 17β-estradiol was compared in male and female isolated perfused rat tail arteries. 17β-Estradiol (10 −7–10 −5 M) attenuated the contractile response to norepinephrine in female, but not male, arteries, but had no effect when the endothelium was removed. Relaxation to 17β-estradiol reached a steady state within approximately 15 min. This hormone appears to acutely relax pre-contracted arteries from females but not males by a non-genomic effect requiring an intact endothelium.