title: Gossypol, a component in cottonseed, induced increases in cytosolic Ca2+ levels in Chang liver cells.
abstract: The effect of gossypol, a compound found in cottonseed, on intracellular free Ca2+ levels ([Ca2+](i)) in Chang liver cells were evaluated using fura-2 as a fluorescent Ca2+ indicator. Gossypol (0.2-5microM) increased [Ca2+](i) in a concentration-dependent manner with an EC(50) value of 1.5microM. The [Ca2+](i) response was composed of an initial rise and a slow decay to a sustained phase within 5min after drug application. Removal of extracellular Ca2+ markedly reduced the [Ca2+](i) signals by 80+/-2%. Preincubation with 0.1mM La3+ or 10microM nimodipine abolished the Ca2+ influx. Gossypol (5microM)-induced release of intracellular Ca2+ was reduced by 75% by pretreatment with 1microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) to deplete the endoplasmic reticulum Ca2+. Conversely, pretreatment with gossypol abolished thapsigargin-induced Ca2+ release. After pretreatment with 5microM gossypol in Ca2+-free medium for several min, addition of 3mM Ca2+ induced a [Ca2+](i) increase of a magnitude nine-fold greater than control. Gossypol (5microM)-induced Ca2+ release was not affected by inhibiting phospholipase C with 2microM 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122). Together, this study shows that gossypol induced significant [Ca2+](i) increases in Chang liver cells by releasing Ca2+ from intracellular pools in a phospholipase C-dissociated fashion and by causing La3+- and nimodipine-sensitive Ca2+ influx.
authors.affiliation: Department of Medicine, Kaohsiung Veterans General Hospital, 386 Ta Chung 1st Road, Taiwan.
authors.forename: J-S
authors.initials: JS
authors.lastname: Cheng
authors.forename: C-P
authors.initials: CP
authors.lastname: Liu
authors.forename: Y-K
authors.initials: YK
authors.lastname: Lo
authors.forename: K-J
authors.initials: KJ
authors.lastname: Chou
authors.forename: M-C
authors.initials: MC
authors.lastname: Lin
authors.forename: W
authors.initials: W
authors.lastname: Su
authors.forename: Y-P
authors.initials: YP
authors.lastname: Law
authors.forename: K-J
authors.initials: KJ
authors.lastname: Chou
authors.forename: J-L
authors.initials: JL
authors.lastname: Wang
authors.forename: W-C
authors.initials: WC
authors.lastname: Chen
authors.forename: C-R
authors.initials: CR
authors.lastname: Jan
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D003369:Cottonseed Oil; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D006072:Gossypol / Q000633:toxicity*; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D009553:Nimodipine / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D002121:Calcium Channel Blockers; D003369:Cottonseed Oil; D004338:Drug Combinations; D004963:Estrenes; D005456:Fluorescent Dyes; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D009553:Nimodipine; D019284:Thapsigargin; D010738:Type C Phospholipases; D006072:Gossypol; D002118:Calcium; D016257:Fura-2