Effect of the antianginal drug bepridil on intracellular Ca2+ release and extracellular Ca2+ influx in human neutrophils.
To understand more fully the effects of bepridil, an antiarrhythmic and antianginal drug, on myocardial ischemia-reperfusion injury and systemic immune responses, its effect on intracellular Ca2+ levels ([Ca2+]i) in human neutrophils was investigated by using fura-2 as a fluorescent probe. Bepridil (10-200 microM) increased [Ca2+]i in a concentration-dependent fashion. This signal was partly inhibited by removal of extracellular Ca2+. In a Ca(2+)-free medium, pretreatment with bepridil (100 microM) abolished the Ca2+ release induced by thapsigargin (1 microM), an endoplasmic reticulum Ca2+ pump inhibitor, and by carbonylcyanide m-chlorophenylhydrazone (2 microM), a mitochondrial uncoupler. Pretreatment with carbonylcyanide m-chlorophenylhydrazone and thapsigargin, respectively, partly inhibited bepridil-induced Ca2+ release. Addition of Ca2+ (3 mM) increased [Ca2+]i after pretreatment with bepridil (100 microM) in a Ca(2+)-free medium. Bepridil (100 microM)-induced Ca2+ release was not altered when phospholipase C was inhibited by U73122 (2 microM). Both Ca2+ release and Ca2+ entry induced by bepridil (100 microM) were augmented by activating protein kinase C with phorbol 12-myristate 13-acetate (10 nM), and were suppressed by inhibiting protein kinase C with GF 109203X (2 microM). Treatment with bepridil (10-20 microM) for 30 min increased the production of reactive oxygen intermediates (ROI) by more than 50%. Collectively, it was found that bepridil increased [Ca2+]i concentration-dependently in human neutrophils by releasing Ca2+ from the endoplasmic reticulum, mitochondria and, possibly, other compartments in a phospholipase C-independent manner. Bepridil also activated Ca2+ influx. The activity of protein kinase C may regulate bepridil-induced Ca2+ release and Ca2+ entry.
Chen
L W
LW
Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
Jan
C R
CR
D000787:Angina Pectoris / Q000188:drug therapy; D015764:Bepridil / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D004963:Estrenes / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D002121:Calcium Channel Blockers; D004963:Estrenes; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D017382:Reactive Oxygen Species; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D015764:Bepridil; D011493:Protein Kinase C; D010738:Type C Phospholipases; D002118:Calcium