title: ET(B) receptor activation causes exocytic insertion of NHE3 in OKP cells.
abstract: Endothelin-1 (ET-1) activates sodium/hydrogen exchanger 3 (NHE3) in opossum kidney clone P (OKP) cells expressing ET(B) receptors. ET-1 (10(-8) M) caused a two- to threefold increase in apical membrane NHE3 (assessed by surface biotinylation), in the absence of a change in total cellular NHE3. A maximal effect was achieved within 15 min. The increase in apical NHE3 was not blocked by cytochalasin D but was blocked by latrunculin B, which also prevented the ET-1-induced increase in NHE3 activity. Endocytic internalization of NHE3, measured as protection of biotinylated NHE3 from the membrane-impermeant, sulfhydryl-reducing agent MesNa was minimal within 35 min and was not regulated by ET-1. Exocytic insertion of NHE3, measured as the appearance of biotinylated NHE3 after the blockade of reactive sites with sulfo-NHS-acetate, was increased in response to ET-1. These studies demonstrate that ET-1 induces net trafficking of NHE3 to the apical membrane that is mediated by enhanced exocytic insertion and is required for increased NHE3 activity.
authors.affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Peng
authors.forename: M
authors.initials: M
authors.lastname: Amemiya
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.forename: L
authors.initials: L
authors.lastname: Fan
authors.forename: O W
authors.initials: OW
authors.lastname: Moe
authors.forename: H
authors.initials: H
authors.lastname: Yin
authors.forename: P A
authors.initials: PA
authors.lastname: Preisig
authors.forename: M
authors.initials: M
authors.lastname: Yanagisawa
authors.forename: R J
authors.initials: RJ
authors.lastname: Alpern
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D019921:Biotinylation; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000502:physiology*; D007700:Kinetics; D009893:Opossums; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
chemical_list: D019332:Endothelin-1; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium; D000469:Alkaline Phosphatase