Muscarinic cholinergic regulation of cardiac myocyte ICa-L is absent in mice with targeted disruption of endothelial nitric oxide synthase
Muscarinic cholinergic regulation of cardiac myocyte ICa-L is absent in mice with targeted disruption of endothelial nitric oxide synthase
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DOI：
10.1073/pnas.95.11.6510
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发表时间：
1998-05-26
影响因子：
11.1
通讯作者：
Kelly, RA
中科院分区：
文献类型：
--
作者：
Han, XQ;Kubota, I;Kelly, RA
心肌细胞已被证明组成性表达内皮一氧化氮合酶 (eNOS)（一氧化氮合酶 3），其激活与心肌细胞 L 型电压敏感钙通道电流 (ICa-L) 和心肌细胞对副交感神经系统信号传导的收缩反应的调节有关，尽管这一含义仍存在争议。因此，我们研究了毒蕈碱胆碱能激动剂卡巴胆碱 (CCh) 对 ICa-L 和异丙肾上腺素 (ISO) 预刺激的心室肌细胞收缩幅度的影响，所述心室肌细胞从成年小鼠（指定为 eNOS(null) 小鼠）中分离出来，并有针对性地破坏 eNOS 基因。虽然 eNOS(null) 和野生型 (WT) 心室肌细胞在 ISO 反应中表现出相似的 ICa-L 增加，但与 WT 小鼠的细胞相比，eNOS(null) 小鼠细胞中的 CCh 没有可测量到的 ICa-L 抑制。这些结果反映了CCh对eNOS(无效)肌细胞中ISO的正性肌力作用没有影响。此外，与 WT 动物的肌细胞不同，eNOS（无效）肌细胞未能表现出响应 CCh 的 cGMP 含量增加。然而，药理学一氧化氮供体 3-吗啉基-西德酮亚胺和 S-亚硝基乙酰半胱氨酸增加了 eNOS（无效）细胞中 cGMP 的生成并抑制了 ISO 增强的 ICa-L，表明 eNOS 下游的信号转导途径保持完整。重要的是，CCh 对乙酰胆碱激活的 K+ 通道的激活在心房和心室 eNOS(null) 肌细胞中不受影响。这些结果证实了 eNOS 在耦合毒蕈碱受体激活与心肌细胞中 ICa-L 的 cGMP 依赖性控制中的必然作用。
Cardiac myocytes have been shown to express constitutively endothelial nitric oxide synthase (eNOS) (nitric oxide synthase 3), the activation of which has been implicated in the regulation of myocyte L-type voltage-sensitive calcium channel current (ICa-L) and myocyte contractile responsiveness to parasympathetic nervous system signaling, although this implication remains controversial. Therefore, we examined the effect of the muscarinic cholinergic agonist carbachol (CCh) on ICa-L and contractile amplitude in isoproterenol (ISO)-prestimulated ventricular myocytes isolated from adult mice, designated eNOS(null) mice, with targeted disruption of the eNOS gene. Although both eNOS(null) and wild type (WT) ventricular myocytes exhibited similar increases in ICa-L in response to ISO, there was no measurable suppression of ICa-L by CCh in cells from eNOS(null) mice, in contrast to cells from WT mice. These results were reflected in the absence of an effect of CCh on the positive inotropic effect of ISO in eNOS(null) myocytes. Also, unlike myocytes from WT animals, eNOS(null) myocytes failed to exhibit an increase in cGMP content in response to CCh. Nevertheless, the pharmacologic nitric oxide donors 3-morpholino-sydnonimine and S-nitroso acetyl-cystein increased cGMP generation and suppressed ISO-augmented ICa-L in eNOS(null) cells, suggesting that the signal transduction pathway(s) downstream of eNOS remained intact. Of importance, activation of the acetylcholine-activated K+ channel by CCh was unaffected in atrial and ventricular eNOS(null) myocytes. These results confirm the obligatory role of eNOS in coupling muscarinic receptor activation to cGMP-dependent control of ICa-L in cardiac myocytes.