一氧化氮在失血性休克大鼠肠运动功能障碍中的作用

The role of nitric oxide on the dysfunction of intestinal motility in rats subjected to hemorrhagic shock

目的 探讨一氧化氮（NO）在失血性休克（HS）大鼠肠运动功能障碍中的作用.方法 16只雄性Wistar大鼠按随机数字表法分组.经股动脉放血复制HS模型；制模后留取十二指肠,分别加入不同诱导物,检测肠管对乙酰胆碱（ACh）的收缩反应,以及肠组织中诱导型一氧化氮合酶（iNOS）活性和NO含量,并进行形态学观察.结果 HS 180 min大鼠肠平滑肌条自发性收缩性和ACh诱发的收缩性均明显降低,与对照组比较,HS组肠平滑肌对ACh的收缩反应降低了近60％ （g· mm-2·s-1：0.40±0.11比1.00±0.20,P＜0.01）；iNOS抑制剂NG-硝基-L-精氨酸甲基酯（L-NAME）可明显逆转HS对十二指肠平滑肌收缩反应的抑制效应（0.97±0.25比0.40±0.11,P＜0.01）,而且,可溶性鸟苷酸环化酶（sGC）抑制剂1H-[1,2,4]恶二唑[4,3-a]喹喔啉-1-酮（ODQ）也可显著改善HS对十二指肠平滑肌条的收缩反应（0.79±0.17比0.40±0.11,P＜0.01）；但ATP敏感性钾通道（KATP）阻断剂格列本脲（Gli）对HS十二指肠平滑肌收缩反应无明显影响（0.47±0.14比0.40±0.11,P＞0.05）.与对照组比较,HS组肠组织iNOS活性（U/g：2.295±0.310比1.319±0.322）和NO含量（μmol/g：2.880±0.353比1.505±0.387）显著升高（均P＜0.01）.光镜下观察HS大鼠十二指肠组织最具特征性的组织形态学改变为炎细胞浸润明显.结论 HS诱导表达的iNOS产生大量NO,通过环磷酸鸟苷酸（cGMP）机制参与了大鼠肠运动功能障碍的发生；而且NO介导的炎细胞浸润也可能参与了HS肠运动功能障碍的发展.

Abstract： Objective To determine the role of nitric oxide （NO） in intestinal motility dysfunction in rats subjected to hemorrhagic shock （HS）.Methods Sixteen male Wistar rats were randomly and equally divided into two groups.The HS model of rat was induced by bleeding from femoral artery.After animal models were made,different inducers were added,and duodenum samples were harvested for the determination of contractile response to acetylcholine （ACh） in vitro,activities of inducible nitric oxide synthase （iNOS）,contents of NO in tissue,and morphological changes.Results The spontaneous contraction of intestinal smooth muscle and contractile response induced by ACh were significantly decreased at 180 minutes in HS group,compared with control group,the contractile response induced by ACh of intestinal smooth muscle was decreased by almost 60% （g· mm-2· s-1：0.40 ± 0.11 vs.1.00 ± 0.20,P〈 0.01）.The inhibitor of iNOS NG-nitro-L-arginine methyl ester hydrochloride （L-NAME） could significantly restore the suppressed contractile response of smooth muscle strips obtained from HS rats （0.97 ± 0.25 vs.0.40 ± 0.11,P〈0.01）.Moreover,the inhibitor of soluble guanylyl cyclase 1 H-[1,2,4] Oxadiazolo [4,3-a] quinoxalin-1-one （ODQ） also improved the contractility of HS muscle strips significantly （0.79 ± 0.17 vs.0.40 ± 0.11,P〈0.01）.But the blocker of ATP-sensitive potassium channel glibenclamide had no effect on the contractility of HS muscle strips （0.47 ± 0.14 vs.0.40 ± 0.11,P〉0.05）.Compared with those of control group,iNOS activities （U/g：2.295 ± 0.310 vs.1.319 ± 0.322）and NO contents （μmol/g：2.880 ± 0.353 vs.1.505-± 0.387） in duodenum of HS rats were both significantly increased （both P〈0.01）.Under light microscopy,the most significant morphological change in duodenum following HS was the infiltration of obvious inflammatory cells.Conclusions The NO produced by the overexpression of iNOS induced by HS involves in the motility dysfunction of intestine through the mechanism of cyclic guanosine monophosphate （cGMP）system.Moreover,NO-mediated infiltration of inflammatory cells in tissue may also contribute to the development of motility dysfunction of intestine following HS.