title: Effect of methoxychlor on Ca(2+) movement and viability in MDCK renal tubular cells.
abstract: The effect of the insecticide methoxychlor on the physiology of renal tubular cells is unknown. This study aimed to explore the effect of methoxychlor on cytosolic Ca(2+) concentrations ([Ca(2+) ](i) ) in MDCK renal tubular cells using the Ca(2+) -sensitive fluorescent dye fura-2. Methoxychlor at 5-20 μM increased [Ca(2+) ](i) in a concentration-dependent manner. The signal was reduced by 80% by removing extracellular Ca(2+) . Methoxychlor-induced Ca(2+) entry was not affected by nifedipine and SK&F96365 but was inhibited by econazole and protein kinase C modulators. In Ca(2+) -free medium, treatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) partly inhibited methoxychlor-induced [Ca(2+) ](i) rise. Incubation with methoxychlor also inhibited thapsigargin- or BHQ-induced [Ca(2+) ](i) rise. Inhibition of phospholipase C with U73122 nearly abolished methoxychlor-induced [Ca(2+) ](i) rise. At 5-15 μM, methoxychlor slightly increased cell viability, whereas at 20 μM, it decreased viability. The cytotoxic effect of methoxychlor was not reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid/AM (BAPTA/AM). Annexin V-FITC data suggest that 10 μM methoxychlor inhibited apoptosis, while 20 μM methoxychlor enhanced apoptosis. Methoxychlor (10 and 20 μM) increased the production of reactive oxygen species. Together, in renal tubular cells, methoxychlor induced [Ca(2+) ](i) rise by inducing phospholipase C-dependent Ca(2+) release from multiple stores and Ca(2+) entry via protein kinase C- and econazole-sensitive channels. Methoxychlor slightly enhanced or inhibited cell viability in a concentration-dependent, Ca(2+) -independent manner. Methoxychlor induced cell death that may involve apoptosis via mitochondrial pathways.
authors.affiliation: Department of Medicine, Chang Bing Show Chwan Memorial Hospital, Changhua County, Taiwan.
authors.forename: He-Hsiung
authors.initials: HH
authors.lastname: Cheng
authors.forename: Yi-Chau
authors.initials: YC
authors.lastname: Lu
authors.forename: Ti
authors.initials: T
authors.lastname: Lu
authors.forename: Jin-Shiung
authors.initials: JS
authors.lastname: Cheng
authors.forename: Guang-Yuan
authors.initials: GY
authors.lastname: Mar
authors.forename: Yi-Chien
authors.initials: YC
authors.lastname: Fang
authors.forename: Kuo-Liang
authors.initials: KL
authors.lastname: Chai
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D004464:Econazole / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D016257:Fura-2; D006873:Hydroquinones / Q000494:pharmacology; D061985:Madin Darby Canine Kidney Cells; D008731:Methoxychlor / Q000633:toxicity*; D009543:Nifedipine / Q000494:pharmacology; D011493:Protein Kinase C / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D017304:Annexin A5; D004963:Estrenes; D006873:Hydroquinones; D011760:Pyrrolidinones; D017382:Reactive Oxygen Species; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C019359:2,5-di-tert-butylhydroquinone; D004533:Egtazic Acid; D019284:Thapsigargin; D004464:Econazole; D011493:Protein Kinase C; D010738:Type C Phospholipases; D009543:Nifedipine; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D008731:Methoxychlor; D002118:Calcium; D016257:Fura-2