Na+/Ca2+ exchanger plays a key role in inducing apoptosis after hypoxia in cultured guinea pig ventricular myocytes
Na+/Ca2+ exchanger plays a key role in inducing apoptosis after hypoxia in cultured guinea pig ventricular myocytes
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DOI：
10.1152/ajpheart.00874.2003
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发表时间：
2004-10-01
影响因子：
4.8
通讯作者：
Hadley, RW
中科院分区：
文献类型：
--
作者：
Eigel, BN;Gursahani, H;Hadley, RW
改变的Na+/Ca2+交换器（NCX）蛋白表达或活性被认为有助于心脏病理的各个方面。在豚鼠心室肌细胞中，ncx介导的Ca2+进入几乎完全负责缺氧再氧化期间Ca2+过载。由于Ca2+超载是细胞凋亡的常见启动剂，本研究的目的是验证以下假设：缺氧再氧化后NCX活性在启动细胞凋亡中起关键作用，并且缺氧再氧化诱导的细胞凋亡可以通过NCX蛋白表达或活性的变化来调节。用NCX反义寡核苷酸降低培养的成年豚鼠心室肌细胞中NCX蛋白的表达。Caspase-3激活和细胞色素c释放作为细胞凋亡的标志。缺氧再氧诱导的细胞凋亡在反义处理的肌细胞中与未处理的对照组或无义处理的肌细胞相比显著减少。内皮素-1或苯肾上腺素预处理培养的肌细胞24 h，可增加NCX蛋白表达，诱发NCX活性，并增强缺氧再氧化诱导的细胞凋亡。对照实验表明，内皮素-1和苯肾上腺素本身不会诱导细胞凋亡，也不会增强Ca2+依赖、ncx独立的细胞凋亡模型中的凋亡反应。另外的对照实验表明，NCX反义寡核苷酸不会改变肌细胞对H2O2或异丙肾上腺素的凋亡反应。综上所述，这些数据表明，NCX在豚鼠肌细胞缺氧再氧化后细胞凋亡的启动中具有关键和特异性的作用，并且缺氧再氧化诱导的细胞凋亡对NCX活性的变化非常敏感。
Altered Na+/Ca2+ exchanger (NCX) protein expression or activity is thought to contribute to various aspects of cardiac pathology. In guinea pig ventricular myocytes, NCX-mediated Ca2+ entry is almost entirely responsible for Ca2+ overload during hypoxia-reoxygenation. Because Ca2+ overload is a common initiator of apoptosis, the purpose of this study was to test the hypotheses that NCX activity is critically involved in initiating apoptosis after hypoxia-reoxygenation and that hypoxia-reoxygenation-induced apoptosis can be modulated by changes in NCX protein expression or activity. An NCX antisense oligonucleotide was used to reduce NCX protein expression in cultured adult guinea pig ventricular myocytes. Caspase-3 activation and cytochrome c release were used as markers of apoptosis. Hypoxia-reoxygenation-induced apoptosis was significantly decreased in antisense-treated myocytes compared with untreated control or nonsense-treated myocytes. Pretreatment of cultured myocytes for 24 h with either endothelin-1 or phenylephrine was found to increase both NCX protein expression and evoked NCX activity as well as enhance hypoxia-reoxygenation-induced apoptosis. Control experiments demonstrated that endothelin-1 and phenylephrine did not induce apoptosis on their own nor did they enhance the apoptotic response in a model of Ca2+-dependent, NCX-independent apoptosis. Additional control experiments demonstrated that the NCX antisense oligonucleotide did not alter the apoptotic response of myocytes to either H2O2 or isoproterenol. Taken together, these data suggest that the NCX has a critical and specific role in the initiation of apoptosis after hypoxia-reoxygenation in guinea pig myocytes and that hypoxia-reoxygenation-induced apoptosis is quite sensitive to changes in NCX activity.