Journal Article

Non-genomic vasorelaxant effects of 17β-estradiol and progesterone on rat aorta are mediated by L- type Ca^2＋ current inhibition

Elisa CAIRRAO Ezequiel ALVAREZ Joao Miguel CARVAS Antonio Jose SANTOS-SILVA Ignacio VERDE

2012

Overview

Aim： The sex hormones 17β-estradiol （13ES） and progesterone （PRG） induce rapid non-genomic vasodilator effects which could be protective for the cardiovascular system. The purpose of this study was to analyze the mechanisms underlying their vasodilator effect in rat aortic smooth muscle preparations. Methods： Endothelium-denuded aorta artery rings were prepared from male Wistar rats and incubated in an organ bath. The contractions of the preparation were recorded through isometric transducers. The effects of the hormones on K^＋ current and L-type Ca^2＋ current （LTCC） were analyzed by using the whole cell voltage-clamp technique in A7r5 cells. Results： Both βES and PRG （1-100 pmol/L） concentration-dependently relaxed the endothelium-denuded aortic rings contracted by （-）-Bay K8644 （0.1 IJmol/L） or by KCl （60 mmol/L）. The IC5o values of the two hormones were not statistically different. The Kvchannel blocker 4-aminopyridine （2 mmol/L）, BKca channel blocker tetraethylammonium （lmmol/L） and KATP channel blocker glibenclamide （10 pmol/L） did not significantly modify the relaxant effect of the hormones. On the other hand, the blockage of the intracellular 13ES and PRG receptors with estradiol receptor antagonists ICI 182,780 （1 pmol/L） and PRG receptor antagonist mifepristone （30 pmol/L）, respectively, did not significantly modify the relaxant action of the hormones. In A7r5 cells, both the hormones （1-100 pmol/L） rapidly and reversibly inhibited the basal and BAY-stimulated LTCC. However, these hormones had no effect on the basal K^＋ current. Conclusion： The vasorelaxant effects of 13ES and PRG are due to the inhibition of LTCC. The K^＋ channels are not involved in the effects.

• Subject: KATP通道 / L-型钙电流 / Wistar大鼠 / 主动脉 / 基因组 / 孕激素 / 血管舒张 / 雌激素