Neuromuscular sensitivity to hydrogen sulfide in the marine invertebrate Urechis caupo.
Neuromuscular sensitivity to hydrogen sulfide in the marine invertebrate Urechis caupo.
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发表时间：
1998-05
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通讯作者：
David Julian;Wendy E. Dalia;A. Arp
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作者：
David Julian;Wendy E. Dalia;A. Arp
硫化氢（HS）通过可逆结合线粒体细胞色素c氧化酶而抑制有氧呼吸，但最近的研究表明HS可能具有其他非呼吸作用。我们研究了HS对体外低氧和缺氧条件下的神经肌肉标本的自发和诱发收缩的影响。收缩幅度响应于电场刺激缺氧条件下完全取消HS在几分钟内在一个经典的剂量-反应关系（Kd=31 mmol L-1，r2=0.86）。暴露的体壁和食管HS在体外长达6小时表明，收缩幅度和频率的自发活动是相对不敏感的缺氧，但HS的敏感性是相似的，在现场刺激的肌肉（Kd=2.7-32 mmol l-1）。HS的毒性作用是可逆的，在缺氧条件下在第一个小时内几乎完全恢复。这些数据表明，在毫摩尔浓度的HS可以直接抑制肌肉收缩。尽管这种作用的机制尚不清楚，但它似乎不涉及代谢途径或氧气运输。
Hydrogen sulfide (HS) is a well-known inhibitor of aerobic respiration via its reversible binding of mitochondrial cytochrome c oxidase, but recent studies have suggested that HS may have other non-respiratory actions. We have studied the effects of HS on spontaneous and evoked contractions in vitro under hypoxic and anoxic conditions in nerve-muscle preparations from the echiuran worm Urechis caupo. Contraction amplitude in response to electric field stimulation under anoxic conditions was completely abolished by HS within minutes in a classic dose-response relationship (Kd=31 mmol l-1, r2=0.86). Exposure of body wall and esophagus to HS in vitro for up to 6 h demonstrated that the contraction amplitude and frequency of spontaneous activity were relatively insensitive to anoxia, but that the sensitivity to HS was similar to that seen in field-stimulated muscle (Kd=2.7-32 mmol l-1). The toxic effects of HS were reversible, with almost complete recovery under anoxic conditions within the first hour. These data indicate that HS at millimolar concentrations can directly inhibit muscle contraction. Although the mechanism of this action is unknown, it does not appear to involve metabolic pathways or oxygen transport.