Activation of distinct cAMP-dependent and cGMP-dependent pathways by nitric oxide in cardiac myocytes
Activation of distinct cAMP-dependent and cGMP-dependent pathways by nitric oxide in cardiac myocytes
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DOI：
10.1161/01.res.84.9.1020
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发表时间：
1999-05-14
影响因子：
20.1
通讯作者：
Sollott, SJ
中科院分区：
文献类型：
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作者：
Vila-Petroff, MG;Younes, A;Sollott, SJ
一氧化氮 (NO) 供体最近被证明可以在心脏组织中产生双相收缩效应，在低 NO 水平时增强，在高 NO 水平时抑制。我们检查了 NO 对心脏收缩的相反作用所涉及的亚细胞机制，并研究了在加载 indo 1 的成年心肌细胞中，NO 是否仅通过鸟苷酸环化酶 (GC) 激活来调节收缩，或者是否通过 cGMP/PKG 独立机制发生某些贡献。高浓度的NO供体S-亚硝基-N-乙酰青霉胺（SNAP，100μmol/L）显着减弱收缩幅度24.4+/-4.5%（不改变Ca2+瞬态或总cAMP），低浓度的SNAP（1μmol/L）显着增加收缩幅度（38+/-10%），Ca2+瞬态 (26+/-10%) 和 cAMP 水平（从 6.2 到 8.5 pmol/mg 蛋白质）。在PKG KT 5823（1μmol/L）特异性阻断剂存在下，100μmol/L SNAP的负收缩反应被完全消除；尽管单独存在GC选择性抑制剂1H-[1,2,4]恶二唑并[4,3-a]喹喔啉-1-一（ODQ，10μmol/L），1μmol/L SNAP的正收缩反应仍持续存在，但在ODQ加特异性抑制性cAMP类似物Rp-8-CPT-cAMPS（100μmol/L）存在下完全消除，如以及由 NO 清除剂氧合血红蛋白。细胞悬浮液中的平行实验表明，低浓度（0.1至1μmol/L）SNAP时腺苷酸环化酶（AC）活性显着增加（AC，比基础活性高18%至20%）。我们得出结论，NO 可以调节心肌细胞中的 AC 和 GC。高水平的 NO 会诱导 cGMP 大幅增加，以及由 PKG 依赖性肌丝对 Ca2+ 反应性降低介导的负性肌力作用。低水平的 NO 至少部分地通过一种新型的不依赖于 cGMP 的 AC 激活来增加 cAMP，并诱导积极的收缩反应。
Nitric oxide (NO) donors were recently shown to produce biphasic contractile effects in cardiac tissue, with augmentation at low NO levels and depression at high NO levels. We examined the subcellular mechanisms involved in the opposing effects of NO on cardiac contraction and investigated whether NO-modulates contraction exclusively via guanylyl cyclase (GC) activation or whether some contribution occurs via cGMP/PKG-independent mechanisms, in indo 1-loaded adult cardiac myocytes. Whereas a high concentration of the NO donor S-nitroso-N-acetylpenicillamine (SNAP, 100 mu mol/L) significantly attenuated contraction amplitude by 24.4+/-4.5% (without changing the Ca2+ transient or total cAMP), a low concentration of SNAP (1 mu mol/L) significantly increased contraction amplitude (38 +/- 10%), Ca2+ transient (26+/-10%), and cAMP levels (from 6.2 to 8.5 pmol/mg of protein). The negative contractile response of 100 mu mol/L SNAP was completely abolished in the presence of the specific blocker of PKG KT 5823 (1 mu mol/L); the positive contractile response of 1 mu mol/L SNAP persisted, despite the presence of the selective inhibitor of GC 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 mu mol/L) alone, but was completely abolished in the presence of ODQ plus the specific inhibitory cAMP analog Rp-8-CPT-cAMPS (100 mu mol/L), as well as by the NO scavenger oxyhemoglobin. Parallel experiments in cell suspensions showed significant increases in adenylyl cyclase (AC) activity at low concentrations (0.1 to 1 mu mol/L) of SNAP (AC, 18% to 20% above basal activity). We conclude that NO can regulate both AC and GC in cardiac myocytes. High levels of NO induce large increases in cGMP and a negative inotropic effect mediated by a PKG-dependent reduction in myofilament responsiveness to Ca2+. Low levels of NO increase cAMP, at least in part, by a novel cGMP-independent activation of AC and induce a positive contractile response.