Mechanisms of carvedilol-induced [Ca2+] i rises and death in human hepatoma cells.
The effect of the cardiovascular drug carvedilol on cytosolic free Ca2+ concentrations ([Ca2+]i) and viability has not been explored in human hepatoma cells. This study examined whether carvedilol altered [Ca2+]i and caused cell death in HA59T cells. [Ca2+]i and cell viability were measured using the fluorescent dyes fura-2 and WST-1, respectively. Carvedilol at concentrations >or=1 microM increased [Ca2+]i in a concentration-dependent manner with an EC50 value of 20 microM. The Ca2+ signal was reduced partly by removing extracellular Ca2+. Carvedilol induced Mn2+ quench of fura-2 fluorescence, implicating Ca2+ influx. The Ca2+ influx was sensitive to La3+, econazole, nifedipine, and SKF96365. In Ca2+-free medium, after pretreatment with 1 muM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), carvedilol-induced [Ca2+]i rises were abolished; and conversely, carvedilol pretreatment inhibited a major part of thapsigargin-induced [Ca2+]i rises. Inhibition of phospholipase C with 2 microM U73122 did not change carvedilol-induced [Ca2+]i rises. At concentrations between 1 and 50 microM, carvedilol killed cells in a concentration-dependent manner. The cytotoxic effect of 1 microM (but not 30 microM) carvedilol was fully reversed by prechelating cytosolic Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA/AM). Apoptosis was induced by 30 (but not 1) microM carvedilol. Collectively, in HA59T hepatoma cells, carvedilol induced [Ca2+]i rises by causing Ca2+ release from the endoplasmic reticulum in a phospholipase-C-independent manner and Ca2+ influx via store-operated Ca2+ channels. Carvedilol-caused cytotoxicity was mediated by Ca2+ and apoptosis in a concentration-dependent manner.
Cheng
Jin-Shiung
JS
Department of Medicine, Yongkang Veterans Hospital, Tainan 710, Taiwan.
Huang
Chorng-Chih
CC
Chou
Chiang-Ting
CT
Jan
Chung-Ren
CR
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002227:Carbazoles / Q000494:pharmacology* / Q000633:toxicity; D006528:Carcinoma, Hepatocellular; D000077261:Carvedilol; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005456:Fluorescent Dyes; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D011412:Propanolamines / Q000494:pharmacology* / Q000633:toxicity; D010738:Type C Phospholipases / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D002614:Chelating Agents; D005456:Fluorescent Dyes; D011412:Propanolamines; D000077261:Carvedilol; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D010738:Type C Phospholipases; D002118:Calcium