Ethanol enhances basal and flow-stimulated nitric oxide synthase activity in vitro by activating an inhibitory guanine nucleotide binding protein.
Ethanol enhances basal and flow-stimulated nitric oxide synthase activity in vitro by activating an inhibitory guanine nucleotide binding protein.
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发表时间：
1999-06
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通讯作者：
Richard J. Hendrickson;Paul A. Cahill;J. Sitzmann;E. Redmond
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作者：
Richard J. Hendrickson;Paul A. Cahill;J. Sitzmann;E. Redmond
本研究的目的是确定乙醇对内皮型一氧化氮合酶(ENOS)的影响，eNOS是一种负责产生重要的血管活性物质一氧化氮的酶。在培养的牛主动脉内皮细胞(EC)上观察乙醇(0.8-160 mM)对基础eNOS和血流刺激eNOS活性的影响。在“静态”EC中，乙醇呈剂量依赖性地增加基础eNOS活性，在40 mM处达到最大反应(约增加2.0倍)，而对细胞活力或一氧化氮合酶蛋白表达没有任何影响。百日咳毒素(PTX)可显著抑制乙醇诱导的eNOS基础活性的升高。内皮细胞暴露于稳定的层流环境中，eNOS活性呈流量和时间依赖性增加。乙醇显著增强层流诱导的eNOS反应，从0.62+/-0.1增加到1.06+/-0。06 pmoL[14C]瓜氨酸/mg/min，该反应可被PTX抑制。在层流暴露EC中，PTX催化的GiAlpha底物核糖化反应(G蛋白功能活性的一个指标)比静态对照增加，乙醇处理进一步增强。同样，EC暴露在低(约0.5dynes/cm2)和高(约12dynes/cm2)脉动血流中显示eNOS活性增加，这一效应与PTX催化的Gipha底物核糖化增加有关。乙醇以PTX敏感的方式增强低流量反应。这些数据表明，乙醇对基础和血流刺激的eNOS活性有刺激作用，部分是通过涉及PTX敏感的G蛋白的机制来调节的。
The aim of this study was to determine the effect of ethanol on endothelial nitric oxide synthase (eNOS), the enzyme responsible for the production of the important vasoactive agent nitric oxide. The effect of ethanol (0.8-160 mM) on both basal and flow-stimulated eNOS activity was determined using cultured bovine aortic endothelial cells (EC). In "static" EC ethanol dose-dependently increased basal eNOS activity with a maximum response (approximately 2.0-fold increase) achieved at 40 mM in the absence of any effect on cell viability or nitric oxide synthase protein expression. Pertussis toxin (PTX) pretreatment significantly inhibited the ethanol-induced increase in basal eNOS activity. EC exposed to steady laminar flow exhibited a flow- and time-dependent increase in eNOS activity. Ethanol significantly enhanced the laminar flow-induced eNOS response from 0.62 +/- 0.1 to 1.06 +/- 0. 06 pmol [14C]citrulline/mg/min, a response that was inhibited by PTX. PTX-catalyzed ribosylation of Gialpha substrates, an index of G-protein functional activity, was increased in laminar flow-exposed EC compared with static controls and was further enhanced by ethanol treatment. Likewise, EC exposed to low ( approximately 0.5 dynes/cm2) and high ( approximately 12 dynes/cm2) pulsatile flow demonstrated increased eNOS activity, an effect that was associated with increased PTX-catalyzed ribosylation of Gialpha substrates. Ethanol enhanced the low flow response in a PTX-sensitive manner. These data demonstrate a stimulatory effect of ethanol on basal and flow-stimulated eNOS activity, mediated in part by a mechanism involving a PTX-sensitive G protein.