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Updated: Jul 11, 2026
Ex Vivo and In Vivo Animal Models for Mechanical and Chemical Injuries of Corneal Epithelium
Published on: April 6, 2022
Ketoconazole-evoked [Ca2+]i rises and non-Ca2+-triggered cell death in rabbit corneal epithelial cells (SIRC)
Muh-Chiou Lin1, Chorng-Chih Huang, Chun-Jen Huang
1Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
Abstract:
The effect of ketoconazole on cytosolic free Ca2+ concentrations ([Ca2+]i) and proliferation has not been explored in corneal cells. This study examined whether ketoconazole alters Ca2+ levels and causes cell death in SIRC rabbit corneal epithelial cells. [Ca2+]i and cell viability were measured by using the fluorescent dyes fura-2 and WST-1, respectively. Ketoconazole at concentrations of 5 microM and above increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca2+. The ketoconazole-induced Ca2+ influx was insensitive to L-type Ca2+ channel blockers and protein kinase C modulators. In Ca2+-free medium, after pretreatment with 50 microM ketoconazole, thapsigargin-(1 microM)-induced [Ca2+]i rises were abolished; conversely, thapsigargin pretreatment nearly abolished ketoconazole-induced [Ca2+]i rises. Inhibition of phospholipase C with 2 microM U73122 did not change ketoconazole-induced [Ca2+]i rises. At concentrations between 5 and 100 microM, ketoconazole killed cells in a concentration-dependent manner. The cytotoxic effect of 50 microM ketoconazole was not reversed by prechelating cytosolic Ca2+ with BAPTA. In summary, in corneal cells, ketoconazole-induced [Ca2+]i rises by causing Ca2+ release from the endoplasmic reticulum and Ca2+ influx from unknown pathways. Furthermore, the cytotoxicity induced by ketoconazole was not caused via a preceding [Ca2+]i rise.
Insights
Ketoconazole increases intracellular calcium ([Ca2+]i) and causes cell death in corneal cells. This occurs through calcium release from the endoplasmic reticulum and influx via unknown routes, independent of initial calcium rise.
Area of Science:
- Ophthalmology
- Cell Biology
- Pharmacology
Background:
- The impact of ketoconazole on corneal cell calcium levels and proliferation remains uninvestigated.
- Corneal epithelial cells are crucial for eye health, and understanding drug effects on them is vital.
Purpose of the Study:
- To investigate the effects of ketoconazole on cytosolic free calcium concentrations ([Ca2+]i) in SIRC rabbit corneal epithelial cells.
- To determine if ketoconazole induces cell death in these corneal cells and elucidate the underlying mechanisms.
Main Methods:
- Utilized fluorescent dyes fura-2 and WST-1 to measure [Ca2+]i and cell viability, respectively.
- Examined the effects of varying ketoconazole concentrations on calcium signaling pathways.
- Investigated the sources of calcium influx and release, including endoplasmic reticulum stores and extracellular sources.
Main Results:
- Ketoconazole elevated [Ca2+]i in a concentration-dependent manner starting at 5 microM.
- Calcium influx was observed but was not mediated by L-type calcium channels or protein kinase C.
- Ketoconazole induced cell death at concentrations between 5 and 100 microM, independent of the preceding calcium increase.
Conclusions:
- Ketoconazole triggers [Ca2+]i increases in corneal cells via calcium release from the endoplasmic reticulum and influx through undetermined pathways.
- Ketoconazole-induced cytotoxicity is not a direct consequence of the initial rise in [Ca2+]i.
