Increased Energy Demand during Adrenergic Receptor Stimulation Contributes to Ca2+ Wave Generation
Increased Energy Demand during Adrenergic Receptor Stimulation Contributes to Ca2+ Wave Generation
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DOI：
10.1016/j.bpj.2015.09.002
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发表时间：
2015-10-20
影响因子：
3.4
通讯作者：
Zima, Aleksey V.
中科院分区：
文献类型：
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作者：
Bovo, Elisa;Mazurek, Stefan R.;Zima, Aleksey V.
虽然β-肾上腺素能受体（β-AR）刺激可确保应激期间有足够的心输出量，但它也可能引发危及生命的心律失常。我们之前已经表明，β-AR 刺激期间致心律失常的 Ca2+ 波在时间上与活性氧 (ROS) 产生的增加同时发生。在本研究中，我们测试了以下假设：β-AR 刺激过程中能量需求的增加在兔心室肌细胞线粒体 ROS 产生和 Ca2+ 波生成中发挥重要作用。我们发现用异丙肾上腺素 (0.1 μM) 刺激 β-AR 会降低线粒体氧化还原电位以及还原型谷胱甘肽与氧化型谷胱甘肽的比率。结果，β-AR 刺激增加了线粒体 ROS 的产生。异丙肾上腺素引起的这些代谢变化与肌浆网 (SR) Ca2+ 渗漏增加和频繁的舒张期 Ca2+ 波相关。使用肌球蛋白 ATP 酶抑制剂 blebbistatin 抑制细胞收缩，可减轻氧化应激以及 β-AR 刺激期间自发的 SR Ca2+ 释放事件。此外，我们发现β-AR刺激诱导的氧化应激导致两个兰尼碱受体（RyR）亚基之间形成二硫键，称为亚基间交联。防止 RyR 与 N-乙基马来酰亚胺交联可降低 β-AR 刺激诱导的 Ca2+ 波的倾向。这些数据表明，持续 β-AR 刺激期间能量需求的增加会削弱线粒体抗氧化防御，导致 ROS 释放到细胞质中。通过诱导 RyR 亚基间交联，ROS 可以将 SR Ca2+ 泄漏增加到可以触发促心律失常 Ca2+ 波的临界水平。
While beta-adrenergic receptor (beta-AR) stimulation ensures adequate cardiac output during stress, it can also trigger life-threatening cardiac arrhythmias. We have previously shown that proarrhythmic Ca2+ waves during beta-AR stimulation temporally coincide with augmentation of reactive oxygen species (ROS) production. In this study, we tested the hypothesis that increased energy demand during beta-AR stimulation plays an important role in mitochondrial ROS production and Ca2+-wave generation in rabbit ventricular myocytes. We found that beta-AR stimulation with isoproterenol (0.1 mu M) decreased the mitochondrial redox potential and the ratio of reduced to oxidated glutathione. As a result, beta-AR stimulation increased mitochondrial ROS production. These metabolic changes induced by isoproterenol were associated with increased sarcoplasmic reticulum (SR) Ca2+ leak and frequent diastolic Ca2+ waves. Inhibition of cell contraction with the myosin ATPase inhibitor blebbistatin attenuated oxidative stress as well as spontaneous SR Ca2+ release events during beta-AR stimulation. Furthermore, we found that oxidative stress induced by beta-AR stimulation caused the formation of disulfide bonds between two ryanodine receptor (RyR) subunits, referred to as intersubunit cross-linking. Preventing RyR cross-linking with N-ethylmaleimide decreased the propensity of Ca2+ waves induced by beta-AR stimulation. These data suggest that increased energy demand during sustained beta-AR stimulation weakens mitochondrial antioxidant defense, causing ROS release into the cytosol. By inducing RyR intersubunit cross-linking, ROS can increase SR Ca2+ leak to the critical level that can trigger proarrhythmic Ca2+ waves.