title: Quercetin and NPPB-induced diminution of aldosterone action on Na+ absorption and ENaC expression in renal epithelium.
abstract: In renal epithelial A6 cells, aldosterone applied for 24 h increased the transepithelial Cl- secretion over 30-fold due to activation of the Na+/K+/2Cl- cotransporter and stimulated the transepithelial Na+ absorption, activity of epithelial Na+ channel (ENaC), and alpha-ENaC mRNA expression. The stimulatory action of aldosterone on the transepithelial Na+ absorption, ENaC activity, and alpha-ENaC mRNA expression was diminished by 24h-pretreatment with quercetin (an activator of Na+/K+/2Cl- cotransporter participating in Cl- entry into the cytosolic space) or 5-nitro 2-(3-phenylpropylamino)benzoate (NPPB) (a blocker of Cl- channel participating in Cl- release from the cytosolic space), while 24h-pretreatment with bumetanide (a blocker of Na+/K+/2Cl- cotransporter) enhanced the stimulatory action of aldosterone on transepithelial Na+ absorption. On the other hand, under the basal (aldosterone-unstimulated) condition, quercetin, NPPB or bumetanide had no effect on transepithelial Na+ absorption, activity of ENaC or alpha-ENaC mRNA expression. These observations suggest that although aldosterone shows overall its stimulatory action on ENaC (transepithelial Na+ transport), aldosterone has an inhibitory action on ENaC (transepithelial Na+ transport) via activation of the Na+/K+/2Cl- cotransporter, and that modification of activity of Cl- transporter/channel participating in the transepithelial Cl- secretion influences the aldosterone-stimulated ENaC (transepithelial Na+ transport).
authors.affiliation: Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Fujimoto
authors.forename: Naomi
authors.initials: N
authors.lastname: Niisato
authors.forename: Tohru
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Marunaka
mesh_terms: D000042:Absorption; D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004347:Drug Interactions; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D007684:Kidney Tubules / Q000187:drug effects / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology*; D011794:Quercetin / Q000494:pharmacology*; D012964:Sodium / Q000493:pharmacokinetics*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D053503:Epithelial Sodium Channels; D009579:Nitrobenzoates; D015222:Sodium Channels; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D000450:Aldosterone; D011794:Quercetin; D012964:Sodium