Pan Chin-Chuan, Cheng He-Hsiung, Huang Chun-Jen, Lu Yih-Chau, Chen I-Shu, Liu Shiuh-Inn, Hsu Shu-Shong, Chang Hong-Tai, Huang Jong-Khing, Chen Jin-Shyr, Jan Chung-Ren
Department of Psychiatry, Kaohsiung Veterans General Hospital, Kaohsiung 813, ROC.
Chin J Physiol. 2006 Dec 31;49(6):290-7.
The effect of the antidepressant mirtazapine on cytosolic free Ca2+ concentration ([Ca2+]i) and viability has not been explored in any cell type. This study examined whether mirtazapine alters Ca2+ levels and causes cell death in osteoblast-like cells using MG63 human osteosarcoma cells as a model. [Ca2+]i and cell viability were measured using the fluorescent dyes fura-2 and WST-1, respectively. Mirtazapine at concentrations above 250 microM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced by 60% by removing extracellular Ca2+. The mirtazapine-induced Ca2+ influx was sensitive to blockade of nifedipine and verapamil. In Ca(2+)-free medium, after pretreatment with 1.5 mM mirtazapine, 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), 2 microM CCCP (a mitochondrial uncoupler), and 1 microM ionomycin failed to release more stored Ca2+; conversely, pretreatment with thapsigargin, CCCP and ionomycin abolished mirtazapine-induced Ca2+ release. Inhibition of phospholipase C with 2 microM U73122 did not change mirtazapine-induced [Ca2+]i, increase. Seal of Ca2+ movement across the plasma membrane with 50 microM extracellular La3+ enhanced 1 microM thapsigargin-induced [Ca2+]i increase, suggesting that Ca2+ efflux played a role in lowering thapsigargin-induced [Ca2+]i increase; however, the same La3+ treatment did not alter mirtazapine-induced [Ca2+]i increase. At concentrations of 500 microM and 1000 microM, mirtazapine killed 30% and 60% cells, respectively. The cytotoxicity was not reversed by chelating cytosolic Ca2+ with BAPTA. Collectively, in MG63 cells, mirtazapine induced a [Ca2+]i increase by causing Ca2+ release from stores and Ca2+ influx from extracellular space. Furthermore, mirtazapine caused cytotoxicity at higher concentrations in a Ca(2+)-dissociated manner.
抗抑郁药米氮平对任何细胞类型胞质游离钙离子浓度（[Ca2+]i）及细胞活力的影响尚未得到研究。本研究以MG63人骨肉瘤细胞为模型，检测米氮平是否会改变成骨样细胞中的钙离子水平并导致细胞死亡。分别使用荧光染料fura-2和WST-1测定[Ca2+]i和细胞活力。浓度高于250微摩尔的米氮平以浓度依赖的方式增加[Ca2+]i。去除细胞外钙离子后，钙离子信号降低了60%。米氮平诱导的钙离子内流对硝苯地平和维拉帕米的阻断敏感。在无钙培养基中，用1.5毫摩尔米氮平预处理后，1微摩尔毒胡萝卜素（一种内质网钙离子泵抑制剂）、2微摩尔CCCP（一种线粒体解偶联剂）和1微摩尔离子霉素未能释放更多储存的钙离子；相反，用毒胡萝卜素、CCCP和离子霉素预处理可消除米氮平诱导的钙离子释放。用2微摩尔U73122抑制磷脂酶C不会改变米氮平诱导的[Ca2+]i增加。用50微摩尔细胞外La3+封闭钙离子跨质膜的移动增强了1微摩尔毒胡萝卜素诱导的[Ca2+]i增加，表明钙离子外流在降低毒胡萝卜素诱导的[Ca2+]i增加中起作用；然而，相同的La3+处理并未改变米氮平诱导的[Ca2+]i增加。在500微摩尔和1000微摩尔浓度下，米氮平分别杀死30%和60%的细胞。用BAPTA螯合胞质钙离子并不能逆转细胞毒性。总体而言，在MG63细胞中，米氮平通过引起钙离子从储存库释放和从细胞外空间内流而诱导[Ca2+]i增加。此外，米氮平在较高浓度下以钙离子解离的方式引起细胞毒性。
