title: AA-861-induced Ca(2+) mobilization in Madin Darby canine kidney cells.
abstract: The effect of 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1, 4-benzoquinone (AA-861), a 5-lipoxygenase inhibitor, on Ca(2+) mobilization in Madin Darby canine kidney (MDCK) cells has been examined by fluorimetry using fura-2 as a Ca(2+) indicator. AA-861 at 10-200 microM increased [Ca(2+)](i) concentration dependently. The signal comprised an initial rise and a sustained phase. Ca(2+) removal inhibited the Ca(2+) signals by reducing both the initial rise and the sustained phase. In Ca(2+)-free medium, pretreatment with 50 microM AA-861 abolished the Ca(2+) release induced by thapsigargin (1 microM), an endoplasmic reticulum Ca(2+) pump inhibitor, and carbonylcyanide m-chlorophenylhydrazone (CCCP; 2 microM), a mitochondrial uncoupler. Pretreatment with CCCP, thapsigargin and gly-phe-beta-naphthylamide to deplete the Ca(2+) stores in mitochondria, the endoplasmic reticulum, and lysosomes, respectively, only partly inhibited AA-861-induced Ca(2+) release. This suggests AA-861 released Ca(2+) from multiple internal pools. Addition of 3 mM Ca(2+) induced a [Ca(2+)](i) rise after pretreatment with 50 microM AA-861 in Ca(2+)-free medium. AA-861 (50 microM)-induced internal Ca(2+) release was not altered by inhibition of phospholipase C with U73122 (2 microM) but was inhibited by 40% by inhibition of phospholipase A(2) with aristolochic acid (40 microM). Collectively, we found that AA-861 increased [Ca(2+)](i) in MDCK cells by releasing Ca(2+) from multiple internal stores in a manner independent of the formation of inositol-1,4,5-trisphosphate, followed by Ca(2+) entry from external medium.
authors.affiliation: Department of Surgery, National Yang Ming University, Taipei, Taiwan.
authors.forename: J K
authors.initials: JK
authors.lastname: Huang
authors.forename: C R
authors.initials: CR
authors.lastname: Jan
mesh_terms: D000818:Animals; D034341:Aristolochic Acids; D016227:Benzoquinones / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005470:Fluorometry; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D010616:Phenanthrenes / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D034341:Aristolochic Acids; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D016859:Lipoxygenase Inhibitors; D010616:Phenanthrenes; D014475:Uncoupling Agents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D019284:Thapsigargin; C036837:2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone; D015544:Inositol 1,4,5-Trisphosphate; C000228:aristolochic acid I; D010741:Phospholipases A; D002118:Calcium