title: W-7 induces [Ca(2+)](i) increases in Madin-Darby canine kidney (MDCK) cells.
abstract: The effect of W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride] on Ca(2+) signaling in Madin-Darby canine kidney cells was investigated. W-7 (0.1-1 mM) induced a [Ca(2+)](i) increase, which comprised an initial increase and a plateau. Ca(2+) removal inhibited the Ca(2+) signals by 80%, suggesting that W-7 activated external Ca(2+) influx and internal Ca(2+) release. Pretreatment with the mitochondrial uncoupler carbonylcyanide m-chlorophenylhydrazone (2 microM) and the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin (1 microM) abolished the internal Ca(2+) release induced by 0.5 mM W-7; conversely, pretreatment with W-7 prevented thapsigargin and carbonylcyanide m-chlorophenylhydrazone from releasing internal Ca(2+). W-7 (0.2 mM) induced Mn(2+) quench of fura-2 fluorescence, which was inhibited by La(3+) (0.1 mM) by 80%. La(3+) (0.1 mM) partly inhibited 0.2 mM W-7-induced [Ca(2+)](i) increase. Addition of 5 mM Ca(2+) induced a significant [Ca(2+)](i) increase after pretreating with 0.2 to 1 mM W-7 in Ca(2+)-free medium for 5 min, suggesting that W-7 induced capacitative Ca(2+) entry. W-7 (0.5 mM) potentiated the capacitative Ca(2+) entry induced by 1 microM thapsigargin by 15%. Pretreatment with aristolochic acid (40 microM) to inhibit phospholipase A(2) reduced 0.5 mM W-7-induced internal Ca(2+) release and external Ca(2+) influx by 25 and 80%, respectively. Inhibition of phospholipase C with U73122 (2 microM) or inhibition of phospholipase D with propranolol (0.1 mM) had no effect on the internal Ca(2+) release induced by 0.5 mM W-7. It remains unclear whether W-7 induced [Ca(2+)](i) increases via inhibition of calmodulin. Three other calmodulin inhibitors (phenoxybenzamine, trifluoperazine, and fluphenazine-N-chloroethane) did not alter resting [Ca(2+)](i).
authors.affiliation: Department of Medical Education and Research, Veterans General Hospital-Kaohsiung, Taiwan, Republic of China. crjan@isca.vghks.gov.tw
authors.forename: C R
authors.initials: CR
authors.lastname: Jan
authors.forename: C J
authors.initials: CJ
authors.lastname: Tseng
mesh_terms: D000818:Animals; D034341:Aristolochic Acids; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002147:Calmodulin / Q000494:pharmacology; D002478:Cells, Cultured; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004963:Estrenes / Q000494:pharmacology; D005453:Fluorescence; D016257:Fura-2; D006835:Hydrazones / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D010616:Phenanthrenes / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors
chemical_list: D034341:Aristolochic Acids; D002147:Calmodulin; D004791:Enzyme Inhibitors; D004963:Estrenes; D006835:Hydrazones; D010616:Phenanthrenes; D011760:Pyrrolidinones; D013449:Sulfonamides; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C017967:W 7; D019284:Thapsigargin; C000228:aristolochic acid I; D011433:Propranolol; D002118:Calcium; D016257:Fura-2