Roles of stretch-activated cation channel and Rho-kinase in the spontaneous contraction of airway smooth muscle
Roles of stretch-activated cation channel and Rho-kinase in the spontaneous contraction of airway smooth muscle
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DOI：
10.1016/j.ejphar.2006.08.067
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发表时间：
2006-12-15
影响因子：
5
通讯作者：
Naruse, Keiji
中科院分区：
文献类型：
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作者：
Ito, Satoru;Kume, Hiroaki;Naruse, Keiji
在豚鼠中，众所周知，气道平滑肌的机械拉伸表现出自发张力，这是由环氧化酶（COX）激活介导的。我们使用药理学方法验证了这种假设，即气道平滑肌的自发收缩是由拉伸激活的非选择性阳离子通道和Rho/Rho激酶途径以及COX-2介导的。在离体豚鼠气管平滑肌组织中评估等长力和细胞内Ca2+浓度（[Ca2+](i)）。将样品拉伸到给定水平，并在等长条件下监测肌肉行为。我们观察到[Ca2+](i)的增加和随后在15分钟内产生的力。通过应用Gd3+（一种拉伸激活通道的抑制剂）和去除细胞外Ca2+，拉伸引起的增强[Ca2+](i)和自发收缩明显减弱。而硝苯地平对子宫收缩只有轻微的抑制作用。(R)-(+)反式- n -（4-吡啶基）-4-（1-氨基乙基）-环己烷-羧酰胺（Y-27632； rho激酶抑制剂）消除自发收缩，[Ca2+]无变化(i)。辛伐他汀可下调Rho活性，也能显著抑制收缩。此外，吲哚美辛（COX-1和-2的抑制剂）和N-[2-（环己氧基）-4-硝基苯基]-甲磺酰胺（NS-398， COX-2抑制剂）消除了拉伸引起的收缩而不影响[Ca2+](i)，而5-（4-氯苯基）-1-（4-甲氧基苯基）-3-（三氟甲基）- 1h -吡唑（SC560， COX-1抑制剂）对收缩的抑制作用要小得多。这些发现表明，Ca2+通过拉伸激活通道、Rho/Rho激酶途径和COX-2进入豚鼠气管平滑肌参与机械转导。此外，虽然Rho/Rho激酶途径和COX-2独立于[Ca2+]调节自发收缩(i)， COX-1不参与拉伸诱导的力的产生。(c) 2006 Elsevier B.V.版权所有
In guinea pigs, it is well-known that mechanical stretch of airway smooth muscle exhibits spontaneous tone which is mediated by cyclooxygenase (COX) activation. We tested the hypothesis that this spontaneous contraction of airway smooth muscle is mediated by stretch-activated non-selective cation channels and the Rho/Rho-kinase pathway, as well as COX-2 using a pharmacological approach. Isometric force and intracellular Ca2+ concentrations ([Ca2+](i)) were assessed in isolated guinea pig tracheal smooth muscle tissues. The samples were stretched to a given level and the muscle behavior was monitored under isometric conditions. We observed an increase in [Ca2+](i) and subsequent force generation over a 15-min period. The augmented [Ca2+](i) and spontaneous contraction due to the stretch were markedly attenuated by application of Gd3+, an inhibitor of stretch-activated channels, and removal of extracellular Ca2+. In contrast, nifedipine only had a mild inhibitory effect on the contraction. (R)-(+)trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexane-carboxamide (Y-27632; a Rho-kinase inhibitor) abolished the spontaneous contraction with no changes in [Ca2+](i). Simvastatin, which down-regulates Rho activity, also significantly inhibited the contraction. Moreover, indomethacin, an inhibitor of COX-1 and -2, and N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS-398; a COX-2 inhibitor) abolished the stretch-induced contraction without affecting [Ca2+](i), whereas the inhibitory effect of 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC560; a COX-1 inhibitor) on the contraction was much less. These findings demonstrated that Ca2+ entry via stretch-activated channels, the Rho/Rho-kinase pathway, and COX-2 are involved in the mechanotransduction in guinea pig tracheal smooth muscle. Additionally, while the Rho/Rho-kinase pathway and COX-2 regulate the spontaneous contraction independently of [Ca2+](i), COX-1 is not involved in the stretch-induced force generation. (c) 2006 Elsevier B.V. All rights reserved.