title: Estrogen acutely inhibits ion transport by isolated stria vascularis.
abstract: We investigated the nongenomic effects of female sex steroid hormones on the short circuit current (I(sc,probe)) across gerbil stria vascularis using the voltage-sensitive vibrating probe. The strial marginal cell epithelial layer produces I(sc,probe) by secreting K+ via I(Ks) channels in the apical membrane. Application of 17beta-estradiol (E2) caused a decrease of I(sc,probe) in a dose-dependent manner (10 nM-10 microM) within seconds. Tamoxifen, a competitive inhibitor of the intracellular estrogen receptor, did not change the inhibitory effect of E2. Activation of I(Ks) channels by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid in the presence and absence of E2 was used to test the mechanism of action. The results were consistent with a direct inhibitory effect of E2 on the I(Ks) channels. By contrast, progesterone caused a transient increase of I(sc,probe). These results suggest that E2 decreases secretion of K+ by inhibition of I(Ks) channels via a nongenomic mechanism at concentrations near those occurring under some physiologic conditions while progesterone caused only transient effects on I(sc,probe).
authors.affiliation: Kansas State University, Department of Anatomy and Physiology, 126 Coles Hall, 1600 Denison Ave., Manhattan, KS 66506, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: D C
authors.initials: DC
authors.lastname: Marcus
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005849:Gerbillinae; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D026902:Potassium Channel Blockers; D011374:Progesterone / Q000494:pharmacology; D013316:Stria Vascularis / Q000187:drug effects / Q000378:metabolism*
chemical_list: D026902:Potassium Channel Blockers; D011374:Progesterone; D004958:Estradiol; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid