Endothelial nitric oxide synthase (eNOS) malfunctioning has been proposed to contribute to the endothelial damage produced by cigarette. Besides eNOS, neuronal NOS (nNOS) is also expressed in most vascular tissues and plays an important role in the endothelium-dependent vascular relaxation. We hypothesize that nNOS may contribute to the endothelium dysfunction produced by cigarette in smokers. Vascular function was assessed in human resistance mesenteric arteries using a wire myograph, the level of protein expression by Western blot, eNOS and nNOS localization by immunofluorescence. Measurement of NO was assessed by fluorescence microscopy. Arteries of smokers showed impaired endothelium-dependent vascular relaxation in response to acetylcholine. Pharmacological nonselective blockade of NOS with l-NAME and selective nNOS blockade with inhibitor 1 reduced the relaxation of the mesenteric artery of both smokers and nonsmokers. Interestingly, the inhibitory effect of NOS inhibitors was greater in nonsmokers than in smokers. The expression of total nNOS and eNOS and the level of phosphorylation at eNOS-pSer1177 were reduced in arteries of smokers as compared with nonsmokers. No differences between groups were observed in the expression of total COX-1, COX-2, catalase and SOD-1. Immunofluorescence analysis showed the presence of nNOS in the vascular endothelium in both groups. Acetylcholine-induced NO production was impaired in arteries from smokers as compared to nonsmokers. Selective inhibition of nNOS caused a decreased in NO production, which was greater in nonsmokers than in smokers. Our data show that a decrease in nNOS expression contributes to the endothelial dysfunction caused by cigarette smoking in human.

中文翻译：

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神经元一氧化氮合酶的表达降低是人类吸烟中内皮功能障碍的原因。

内皮一氧化氮合酶（eNOS）的功能异常被认为是导致卷烟对内皮的损害。除eNOS以外，神经元NOS（nNOS）还表达于大多数血管组织中，并在依赖内皮的血管舒张中发挥重要作用。我们假设nNOS可能导致吸烟者吸烟引起的内皮功能障碍。使用钢丝肌电图仪评估人抵抗力肠系膜动脉中的血管功能，通过蛋白质印迹，eNOS和nNOS定位（通过免疫荧光）评估蛋白质表达水平。通过荧光显微镜评估NO的测量。吸烟者的动脉显示出对乙酰胆碱的响应受损的内皮依赖性血管舒张功能。用l-NAME进行药理学上的非选择性NOS阻断和用抑制剂1进行选择性nNOS阻断可减少吸烟者和不吸烟者的肠系膜动脉舒张。有趣的是，NOS抑制剂在不吸烟者中的抑制作用大于在吸烟者中。与不吸烟者相比，吸烟者动脉中总nNOS和eNOS的表达以及eNOS-pSer1177的磷酸化水平降低。总COX-1，COX-2，过氧化氢酶和SOD-1的表达在两组之间没有差异。免疫荧光分析显示两组血管内皮中均存在nNOS。与不吸烟者相比，吸烟者的动脉胆碱胆碱诱导的一氧化氮生成受到损害。对nNOS的选择性抑制导致NO生成量的减少，这在不吸烟者中比在吸烟者中更大。