Effects of apocynin on ISO-induced delayed afterdepolarizations in rat atrial myocytes and the underlying mechanisms
Effects of apocynin on ISO-induced delayed afterdepolarizations in rat atrial myocytes and the underlying mechanisms
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罗布麻宁对ISO诱导的大鼠心房肌细胞延迟后除极的影响及其机制
DOI：
10.1016/j.bbrc.2022.11.053
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发表时间：
01
影响因子：
3.1
通讯作者：
Yang Li
中科院分区：
文献类型：
--
作者：
Nan Zhang;Qing Dan;Ying Dong;Yan Liu;Wenjuan Zhuang;Zhonghui Xie;Qianqian Zhao;Kun Lin;Yang Li
本研究旨在探讨夹竹桃素（APO）对大鼠心房肌细胞延迟后除极（DADs）的影响及其机制。用Langendorff灌流仪分离大鼠心房肌细胞。异丙肾上腺素（ISO）诱导DAD。采用全细胞钳技术记录动作电位（AP）和离子电流。荧光指示剂fluo-4用于观察细胞内Ca 2+瞬变，并使用western blotting来测量相关蛋白的表达。ISO处理后，大鼠心房肌细胞DAD的发生率显著增加，导致触发活动（TA）的发生率增加。100.0 μM APO可使ISO诱导的DAD和TA的发生率分别从48.89%和17.78%降至25.56%和5.56%。在3.0 μM-300.0 μM范围内，APO的作用呈浓度依赖性，半最大抑制浓度（IC 50）为120.1 μM，希尔系数为1.063。APO可逆转ISO引起的心房肌细胞瞬时内向电流（Iti）和Na+/Ca ~（2+）交换电流（INCX）的增加。100.0 μM APO可降低心房肌细胞自发性钙瞬变的频率。与ISO相比，APO可下调NOX 2的表达，增加PLNSer 16磷酸化水平和肌浆网Ca ~（2+）-ATPase-2a（SERCA 2a）水平，但对RyR 2影响不大。这些结果表明，APO可阻断ItiandINCX，降低大鼠心房肌细胞内Ca ~（2+）水平，从而减少ISO诱导的DAD和TA的发生。
We aimed to investigate the effect of apocynin (APO) on delayed afterdepolarizations (DADs) in rat atrial myocytes and the underlying mechanisms. Rat atrial myocytes were isolated by a Langendorff perfusion apparatus. DADs were induced by isoproterenol (ISO). Action potentials (APs) and ion currents were recorded by the whole-cell clamp technique. The fluorescent indicator fluo-4 was used to visualize intracellular Ca2+transients, and western blotting was used to measure the expression of related proteins. The incidence of DADs in rat atrial myocytes increased significantly after ISO treatment, leading to an increased incidence of triggered activity (TA). The incidence of ISO-induced DADs and TA were reduced by 100.0 μM APO from 48.89% to 25.56% and 17.78% to 5.56%, respectively. In the range of 3.0 μM–300.0 μM, the effect of APO was concentration dependent, with a half maximal inhibitory concentration (IC50) of 120.1 μM and a Hill coefficient of 1.063. APO reversed the increase in transient inward current (Iti) and Na+/Ca2+-exchange current (INCX) densities induced by ISO in atrial myocytes. The frequency of spontaneous Ca2+transients in atrial myocytes was reduced by 100.0 μM APO. Compared with ISO, APO downregulated the expression of NOX2 and increased the phosphorylation of PLNSer16and the sarcoplasmic reticulum Ca2+-ATPase-2a (SERCA2a) level; however, it had little effect on ryanodine-receptor channel type-2 (RyR2). These findings showed that APO may block Itiand INCXand reduce intracellular Ca2+levels in rat atrial myocytes, thus reducing the incidence of ISO-induced DADs and TA.