Gossypol, a component in cottonseed, induced increases in cytosolic Ca2+ levels in Chang liver cells.
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.
Cheng
J-S
JS
Department of Medicine, Kaohsiung Veterans General Hospital, 386 Ta Chung 1st Road, Taiwan.
Liu
C-P
CP
Lo
Y-K
YK
Chou
K-J
KJ
Lin
M-C
MC
Su
W
W
Law
Y-P
YP
Chou
K-J
KJ
Wang
J-L
JL
Chen
W-C
WC
Jan
C-R
CR
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
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