title: MK-886, a leukotriene biosynthesis inhibitor, as an activator of Ca(2+) mobilization in Madin-Darby canine kidney (MDCK) cells.
abstract: The effect of 3-¿1-(p-chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl-2, 2-dimethylpropanoic acid (MK-886), a leukotriene biosynthesis inhibitor, on Ca(2+) mobilization in Madin- Darby canine kidney cells has been examined by fluorimetry using fura-2 as a Ca(2+) indicator. MK-886 at 0.5 to 25 microM concentration dependently increased ¿Ca(2+)(i). The ¿Ca(2+)(i) increase comprised an immediate initial rise and a slowly decaying phase. Ca(2+) removal inhibited the Ca(2+) signals by reducing both the initial rise and the decay phase, suggesting that MK-886 activated Ca(2+) influx and Ca(2+) release. In Ca(2+)-free medium, 10 microM MK-886 still increased ¿Ca(2+)(i) after pretreatment with carbonylcyanide m-chlorophenylhydrazone (CCCP; 2 microM), a mitochondrial uncoupler, and thapsigargin (1 microM), an endoplasmic reticulum Ca(2+) pump inhibitor. Conversely, pretreatment with MK-886 abolished CCCP- and thapsigargin-induced Ca(2+) release. This suggests that 10 microM MK-886 released Ca(2+) from the endoplasmic reticulum, mitochondria, and other stores. The addition of 3 mM Ca(2+) increased ¿Ca(2+)(i) after pretreatment with 10 microM MK-886 for 700 s in Ca(2+)-free medium, indicating that MK-886 induced capacitative Ca(2+) entry. This capacitative Ca(2+) entry was partly inhibited by SKF96365 (50 microM), by econazole (25 microM), and by inhibiting phospholipase A(2) with aristolochic acid (40 microM) but not by inhibiting phospholipase D with 0.1 mM propranolol. MK-886 (10 microM)-induced Ca(2+) release was not altered by inhibiting phospholipase C with U73122 (2 microM) but was inhibited by 50% by suppressing phospholipase D and phospholipase A(2) with propranolol (0.1 mM) and aristolochic acid (40 microM), respectively.
authors.affiliation: Department of Medical Education and Research, Veterans General Hospital-Kaohsiung, Kaohsiung, Taiwan. 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; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004963:Estrenes / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D011760:Pyrrolidinones / Q000494:pharmacology; D002722:Chlorobenzenes
chemical_list: D002118:Calcium; D004963:Estrenes; D007211:Indoles; D016859:Lipoxygenase Inhibitors; D011760:Pyrrolidinones; C060893:MK-886; D002722:Chlorobenzenes; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione