Effect of clotrimazole on cytosolic Ca(2+) rise and viability in HA59T human hepatoma cells.

Abstract Clotrimazole is an antimycotic imidazole derivative that interferes with cellular Ca(2+) homeostasis. This study examined the effect of clotrimazole on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in HA59T human hepatoma cells. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i). Clotrimazole induced [Ca(2+)](i) rises in a concentration-dependent manner. The response was reduced by removing extracellular Ca(2+). Clotrimazole-evoked Ca(2+) entry was suppressed by store-operated channel inhibitors (nifedipine, econazole and SK&F96365) and protein kinase C modulators (GF109203X and phorbol, 12-myristate, 13-acetate). In Ca(2+)-free medium, incubation with the endoplasmic reticulum Ca(2+) pump inhibitor 2,5-di-tert-butylhydroquinone abolished clotrimazole-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 abolished clotrimazole-induced [Ca(2+)](i) rise. At 10-40 µM, clotrimazole inhibited cell viability, which was not reversed by chelating cytosolic Ca(2+). Clotrimazole at 10 and 30 µM also induced apoptosis. Collectively, in HA59T cells, clotrimazole-induced [Ca(2+)](i) rises by evoking phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via store-operated Ca(2+) channels. Clotrimazole also caused apoptosis.