Abstract
Captopril, an angiotensin-converting enzyme (ACE) inhibitor, induced different Ca 2+ signaling responses in various cell models. However, the effect of captopril on Ca 2+ homeostasis and cell viability in hepatoma cells is unknown. This study examined whether captopril altered Ca 2+ homeostasis and viability in HepG2 human hepatoma cells. Intracellular Ca 2+ concentrations in suspended cells were monitored by using the fluorescent Ca 2+ -sensitive dye fura-2. Cell viability was examined by using 4-[3-[4-lodophenyl]-2-4(4-nitrophenyl)-2H-5-tetrazolio-1,3-benzene disulfonate] water soluble tetrazolium-1 (WST-1). Captopril at concentrations of 500-3000 µM induced cytosolic free concentrations of Ca 2+ ([Ca 2+ ] i ) rises in a concentration-dependent manner. Ca 2+ removal reduced the signal by approximately 15%. Mn 2+ has been shown to enter cells through similar mechanisms as Ca 2+ but quenches fura-2 fluorescence at all excitation wavelengths. Captopril (3000 μM)-induced Mn 2+ influx indirectly suggested that captopril evoked Ca 2+ entry. Captopril-induced Ca 2+ entry was inhibited by 15% by a protein kinase C (PKC) activator (phorbol 12-myristate 13 acetate, PMA) and an inhibitor (GF109203X) and three inhibitors of store-operated Ca 2+ channels: nifedipine, econazole and SKF96365. In Ca 2+ -free medium, treatment with the endoplasmic reticulum Ca 2+ pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) abolished captopril-evoked [Ca 2+ ] i rises. Conversely, treatment with captopril abolished BHQ-evoked [Ca 2+ ] i rises. Inhibition of phospholipase C (PLC) with U73122 inhibited 70% of captopril-induced [Ca 2+ ] i rises. Captopril at concentrations between 150- 550 μM killed cells in a concentration-dependent fashion. Chelation of cytosolic Ca 2+ with 1,2-bis(2- aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid/acetoxy methyl (BAPTA/AM) did not reverse captopril’s cytotoxicity. Together, in HepG2 human hepatoma cells, captopril induced [Ca 2+ ] i rises and caused cell death that was not triggered by preceding [Ca 2+ ] i rises.
Original language | English |
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Pages (from-to) | 221-229 |
Number of pages | 9 |
Journal | Chinese Journal of Physiology |
Volume | 61 |
Issue number | 4 |
DOIs | |
State | Published - 2018 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2018 by The Chinese Physiological Society.
Keywords
- Ca
- Captopril
- Endoplasmic reticulum
- Human hepatoma cells
- Viability