Econazole-evoked [Ca2+]i Rise and Non-Ca2+-triggered Cell Death in Rabbit Corneal Epithelial Cells (SIRC) |
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Authors: | Jau-Min Chien Chorng-Chih Huang He-Hsiung Cheng Wei-Chuan Chen Pi-Lai Tseng |
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Affiliation: | 1. Department of Medicine, Ping Tung Christian Hospital, Ping Tung, Taiwan 900;2. Department of Nursery, Tzu Hui Institute of Technolog, Ping Tung, Taiwan 926;3. Section of Allergy, Immunology &4. Rheumatology, Chi-Mei Medical Center, Tainan, Taiwan 710;5. Department of Pharmacy, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan 813 |
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Abstract: | The effects of econazole, an antifungal drug applied for treatment of keratitis and mycotic corneal ulcer, on cytosolic-free Ca2+ concentrations ([Ca2+]i) and viability of corneal cells was examined by using SIRC rabbit corneal epithelial cells as model. [Ca2+]i and cell viability were measured by using the fluorescent dyes fura-2 and WST-1, respectively. Econazole at concentrations ≥ 1 µM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca2+. The econazole-induced Ca(2+) influx was insensitive to L-type Ca2+ channel blockers and protein kinase C modulators. In Ca2+-free medium, after pretreatment with 20 µM econazole, [Ca2+]i rises induced by 1 µM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) were abolished. Conversely, thapsigargin pretreatment also abolished econazole-induced [Ca2+]i rises. Inhibition of phospholipase C with 2 µM U73122 did not change econazole-induced [Ca2+]i rises. At concentrations between 10 and 80 µM, econazole killed cells in a concentration-dependent manner. The cytotoxic effect of 20 µM econazole was not reversed by prechelating cytosolic Ca2+ with BAPTA. This shows that in SIRC cells econazole induces [Ca2+]i rises by causing Ca2+ release from the endoplasmic reticulum and Ca2+ influx from unknown pathways. Econazole-caused cytotoxicity was independent from a preceding [Ca2+]i rise. |
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Keywords: | Ca2+ Corneal cells Econazole Fura-2 SIRC WST-1 |
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