title: Endothelin-1 aggravates hypoxia/reoxygenation-induced injury in renal epithelial cells through the activation of a Na+/Ca2+ exchanger.
abstract: We analyzed the role of the Na/Ca2+ exchanger (NCX) in hypoxia/reoxygenation-induced injury and also its interaction with endothelin-1 in the proximal epithelial cell line LLC-PK1. The hypoxia/reoxygenation protocol caused a significant leakage of lactate dehydrogenase from parental LLC-PK1 cells, which was markedly suppressed by KB-R7943, a selective NCX inhibitor. Overexpression of wild-type NCX1 into LLC-PK1 cells enhanced the release of lactate dehydrogenase and produced more severe morphological changes, such as bleb formation, during reoxygenation. Endothelin-1 significantly aggravated hypoxia/reoxygenation- induced injuries in parental and NCX1-overexpressing LLC-PK1 cells. Such aggravation by endothelin-1 was not observed in cells overexpressing a deregulated NCX1 mutant, which displays no protein kinase C-dependent activation. KB-R7943 suppressed those cell injuries aggravated by endothelin-1, but not those in cells overexpressing a KB-R7943-insensitive NCX1 mutant. We confirmed that these cell injuries were relevant to their cellular Ca accumulations induced by hypoxia/reoxygenation. These results suggest that Ca2+ overload via NCX plays a critical role in hypoxia/reoxygenation-induced renal tubular injury, and that endothelin-1 aggravates the cell damage through the activation of NCX.
authors.affiliation: Department of Pharmacology, School of Medicine, Fukuoka University, Fukuoka, Japan. tiwamoto@cis.fukuoka-u.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Satomi
authors.initials: S
authors.lastname: Kita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Katsuragi
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia; D002470:Cell Survival; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D018374:LLC-PK1 Cells; D009154:Mutation; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D014162:Transfection
chemical_list: C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; D019332:Endothelin-1; D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1; D013890:Thiourea; D002118:Calcium