结肠黏膜Trx的表达与肠易激综合征发病机制的相关性研究

目的观察硫氧还蛋白(Trx)在腹泻型肠易激综合征(IBS-D)和便秘型肠易激综合征(IBS-C)患者结肠黏膜中的表达情况,探讨肠易激综合征(IBS)的发病机制。方法选择2017年1月至2019年4月解放军总医院消化门诊收治的IBS-D、IBS-C患者各16例,分别设为IBS-D组和IBS-C组,另选择健康志愿者16例作为对照组,活检留取盲肠及乙状结肠黏膜组织,应用免疫组织化学染色分析。Western blot和荧光定量PCR法检测Trx及Trx mRNA表达情况。结果免疫组织化学染色显示,在正常结肠腺上皮细胞、隐窝上皮细胞、上皮基底膜和固有层间质细胞均可见Trx阳性表达。Western blot显示,Trx在IBS-D组和IBS-C组盲肠及乙状结肠的表达均明显高于对照组(P 0.05)。荧光定量PCR结果提示,与对照组比较,Trx mRNA在IBS-D组和IBS-C组盲肠黏膜的表达明显下调(P 0.05),在IBS-D组和IBS-C组乙状结肠黏膜的表达明显上调(P 0.01)。结论 IBS发病机制可能与Trx相关的氧化应激、能量代谢异常及免疫稳态失衡相关。     

2.64腹泻型、便秘型肠易激综合征患者肠黏膜一氧化氮含量变化初步探讨

目的用消化道腔内测压技术以及生物化学的方法研究IBS患者肠动力、肠内脏感觉、肠黏膜内的NO含量的变化,探讨NO与腹泻型、便秘型IBS患者的肠动力异常和内脏感觉异常的关系.探讨NO在IBS发病机制中的作用.     

大鼠肢体缺血再灌注致肺损伤时肺内一氧化氮对一氧化碳的影响及其分子机制

目的观察肢体缺血再灌注致肺损伤时肺内一氧化氮(NO)对一氧化碳(CO)的影响及其分子机制.方法夹闭大鼠腹主动脉下段造成双后肢缺血及再灌注后肺损伤模型.将动物随机分为4组假手术(sham)组、缺血4h再灌注8h组(1/R)、sham+氨基胍(aminoguanidine,AG)组和I/R+AG组.后两组于再灌注2h或相应的假手术时间点给予舌静脉注射诱生型一氧化氮合酶(inducible nitric oxidesynthase,iNOS)阻断剂-AG,前两组给予等量溶剂处理.分别以Northernblotting和Westernblotting的方法检测肺组织中诱导型血红素氧化酶(hemeoxygenase-1,HO-1)mRNA和蛋白表达的变化;免疫组化的方法检测核转录因子一活化蛋白-1(activatorprotein-1,AP-1)的两个亚单位-c-fos和c-jun的免疫组化染色的变化;以CO血氧检测仪检测动脉血内碳氧血红蛋白(COHb)水平变化;以硝酸还原法检测肺组织匀浆中NO代谢产物NO-2/NO-3含量的变化.结果与sham组相比,I/R组肺组织中NO-2/NO-3含量和血内COHb水平显著增高(P＜0.05),肺组织中HO-1mRNA和蛋白表达增强,肺组织中c-fos和c-jun的免疫组化染色亦显著增强.与I/R组相比,I/R+AG组肺组织中NO-2/NO-3含量显著减少(P＜0.05),同时血内COHb水平、肺内HO-lmRNA和蛋白表达以及c-fos和c-jun的免疫组化染色均显著减弱.讨论我室研究已证实肢体缺血再灌注致肺损伤时肺组织中iNOS和HO-l表达以及NO和CO的生成显著增多,并发挥不同的重要作用.本实验通过观察iNOS阻断剂-AG减少NO产生后对CO的影响,发现肢体缺血再灌注致肺损伤时肺组织中iNOS的诱生以及NO的大量生成能够促使CO产生增多;通过对HO-l表达的检测表明,NO对CO的影响是通过调控HO-l表达所实现的,而AP-l可能参与了NO对HO-1表达调控作用的信号转导机制.结论肢体缺血再灌注致肺损伤时肺内iNOS诱生以及NO的过量生成具有上调HO-l表达使CO产生增多的作用,核因子AP-l可能参与了NO对HO-l调控的信号转导机制.     

大鼠肢体缺血再灌注致肺损伤时肺内一氧化碳对一氧化氮的影响

目的观察肢体缺血再灌注致肺损伤时肺内一氧化碳(CO)对一氧化氮(NO)及其衍生物过氧亚硝基阴离子(ONOO-)的影响.方法夹闭大鼠腹主动脉下段造成双后肢缺血及再灌注后肺损伤模型.将动物随机分为4组假手术(sham)组、缺血4h再灌注16h(1/R)组、Sham十锌原卟啉(zinc protoporphyrin,ZnPP)组和I/R+ZnPP组.后两组于再灌注前15min或相应的假手术时间点给予舌静脉注射血红素氧化酶(heme oxygenase,HO)阻断剂-ZnPP,前两组给予等量溶剂处理.以CO-血氧检测仪检测动脉血内碳氧血红蛋白(COHb)水平变化;以Northernblotting检测肺组织中诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)mRNA表达的变化;以比色法检测肺组织NOS活性;以硝酸还原法检测肺组织匀浆中NO代谢产物NO-2/NO-3含量的变化.结果与sham组相比,I/R组血内COHb水平、肺组织中NO-2/NO-3含量和NOS活性均显著升高(P＜0.05),iNOSmRNA表达以及NT的免疫组化染色显著增强表达.与I/R组相比,I/R+ZnPP组血内COHb水平显著减低(P＜0.05),肺组织中NO-2/NO-3含量和NOS活性均显著升高(P＜0.05);iNOSmRNA表达未见显著变化.讨论我室研究已证实肢体缺血再灌注致肺损伤时肺组织中iNOS和HO-l表达上调、NO和CO的生成显著增多,并发挥不同的重要作用.本实验通过观察HO阻断剂-ZnPP减少CO产生后对NO的影响,发现抑制HO活性使CO产生减少后,肺组织中NO生成增多,表明肢体缺血再灌注致肺损伤时肺组织中HO-1的诱生以及CO的大量生成具有减少NO产生的作用;通过对iNOSmRNA表达和NOS活性的检测表明,CO对NO的影响是通过影响NOS活性而实现的,可能与iNOSmRNA表达无关.结论肢体缺血再灌注致肺损伤时肺内HO-l的诱生以及CO的大量生成具有抑制NOS活性从而使NO产生减少的作用.     

2.89肠易激综合症患者回结肠黏膜VIP活性与结肠动力的关系研究

目的通过对IBS患者回结肠黏膜上皮细胞内肽类激素-血管活性肠肽(VIP)免疫活性的测定,研究其在细胞内含量与IBS患者的不同症状关系,探讨IBS的发病机理,指导临床治疗. 方法选择IBS患者80例,每位患者通过结肠镜检查取回结肠结合处黏膜3块,采用免疫组化方法对肠粘膜组织进行处理、染色.     

2.98肠易激综合征时结肠黏膜一氧化氮含量的临床观察

目的本研究通过观察IBS患者结肠粘膜组织中的NO含量,拟对NO在IBS发病机制中的作用作一探讨. 方法对临床表现腹痛、排便异常患者行结肠镜检查,排除结肠器质性病变、炎症性肠病、同时排除糖尿病,慢性肝病等慢性疾病的患者,且符合RomeⅡ诊断标准者59例,正常对照组20例,共分为三组:1.腹泻组:大便次数增多,每天大便大于3次,共36例,男10例,女26例,平均年龄45.23±10.59岁;     

肠易激综合症患者回结肠黏膜VIP活性与结肠动力的关系研究

目的　通过对IBS患者回结肠黏膜上皮细胞内肽类激素—血管活性肠肽 (VIP)免疫活性的测定 ,研究其在细胞内含量与IBS患者的不同症状关系 ,探讨IBS的发病机理 ,指导临床治疗。方法　选择IBS患者 80例 ,每位患者通过结肠镜检查取回结肠结合处黏膜 3块 ,采用免疫组化方法对肠粘膜组织进行处理、染色。然后光镜下观察进行分析。依据不同临床表现将患者分为 3组 :腹泻组 (腹泻为主 ) 30例 ;便秘组 (便秘为主 ) 2 0例 ;混合组 (腹泻、便秘交替 ) 30例。选择外科手术后的远端结肠作为对照。各组IBS患者回结肠结合处黏膜标本按阳性染色积分并…     

腹泻型、便秘型肠易激综合征患者肠黏膜一氧化氮含量变化初步探讨

目的　用消化道腔内测压技术以及生物化学的方法研究IBS患者肠动力、肠内脏感觉、肠黏膜内的NO含量的变化 ,探讨NO与腹泻型、便秘型IBS患者的肠动力异常和内脏感觉异常的关系。探讨NO在IBS发病机制中的作用。方法　 1 应用电子气压泵及灌注导管测压仪研究 30例腹泻型IBS患者、30例便秘型IBS患者及2 5例健康对照组的肛门、直肠压力、直肠顺应性、乙状结肠和直肠运动指数以及直肠对容量刺激的感觉阈值 ;2 应用硝酸还原酶法测定三组肠黏膜NO的含量。结果　 1 肛门直肠压力 :腹泻型、便秘型IBS患者的直肠静息压、肛管上部静息压、收…     

硫化氢对肢体缺血再灌注所致大鼠急性肺损伤的作用及机制

目的: 探讨内、外源性硫化氢(H₂S)在肢体缺血再灌注(IR)所致大鼠急性肺损伤(ALI)中的作用并初探其机制。方法: 应用双大腿根部止血带复制大鼠双后肢缺血及再灌注后肺损伤模型。将120只SD大鼠随机分为对照组(control)、IR组、NaHS+IR组和抑制H₂S生成的炔丙基甘氨酸(PPG)+IR组。肢体缺血再灌注后4 h处死动物, 测定肺系数;光镜下观察肺组织形态学改变;化学法检测血浆H₂S、NO、CO含量,肺组织丙二醛(MDA)含量、胱硫醚-γ-裂解酶(CSE)、诱导型一氧化氮合酶(iNOS)和血红素加氧酶(HO)活性以及支气管肺泡灌洗液(BALF)中中性粒细胞(PMN)数目和蛋白含量变化,并对血浆H₂S含量与上述指标进行相关性分析。结果: 大鼠肢体IR可引起肺组织明显的形态学改变、肺系数和肺组织MDA含量增加、BALF中PMN数目和蛋白含量增加、血浆H₂S含量和肺组织CSE活性下降、肺组织iNOS活性和HO活性及血浆中NO含量和CO含量增加。预先给予NaHS可显著减轻IR所致上述指标的改变; 而预先给予PPG可加重IR所致肺损伤, 使BALF中PMN数目和蛋白含量、血浆NO含量和肺组织iNOS活性进一步增加, 但对血浆CO含量和肺组织HO活性无明显影响。H₂S含量与CSE活性、血浆CO含量、肺组织HO活性呈正相关(均P<0.01);与其它指标呈负相关(均P<0.01)。结论: H₂S/CSE体系的下调参与介导了大鼠肢体IR所致大鼠ALI的发生, 内、外源性H₂S具有抗肢体IR所致ALI的作用, 该作用可能与其抗氧化效应、减轻PMN所致肺部过度炎症反应以及下调NO/iNOS体系、上调CO/HO体系有一定关系。     

原发性高血压患者血清NO、NOS及其亚型水平的分析

目的:测定原发性高血压患者外周血中血清一氧化氮(NO)、一氧化氮合酶(NOS)及其亚型水平,探讨NO/NOS系统参与血压调节的可能机制.方法:原发性高血压患者135例,正常对照组35例.采用化学法检测所有病例外周血的一氧化氮(NO)、总NOS、诱导型一氧化氮合酶(iNOS)和结构型一氧化氮合酶(cNOS)水平并作统计学分析.结果:高血压组NO、NOS、iNOS和cNOS水平均低于正常对照组,且差异具有显著性意义(分别为:P＜0.05,P＜0.01,P＜0.01,P＜0.01);iNOS/cNOS比值与正常对照组相比无显著差异(P＞0.05);对照组和高血压组的NOS浓度与iNOS和cNOS浓度均呈显著正相关;高血压组的cNOS水平与iNOS水平呈显著负相关.结论:高血压患者NO、NOS及其亚型浓度值可以作为临床评估高血压的参考指标;iNOS在正常人体内有表达;在高血压情况下,机体有通过增加iNOS的表达来弥补cNOS水平的病理性降低、调控NOS总体水平从而调节和平衡血压的趋势.     

Opposite effect of oxidative stress on inducible nitric oxide synthase and haem oxygenase-1 expression in intestinal inflammation: anti-inflammatory effect of carbon monoxide

Inducible nitric oxide synthase (iNOS) is expressed in intestinal epithelial cells (IEC) of patients with active inflammatory bowel disease (IBD) and in IEC of endotoxaemic rats. The induction of iNOS in IEC is an element of the NF-kappaB-mediated survival pathway. Haem oxygenase-1 (HO-1) is an AP-1-regulated gene that is induced by oxidative stress. The enzyme produces carbon monoxide (CO), which may attenuate the inflammatory response. The aim of this study was to investigate the regulation and interaction of iNOS and HO-1 in response to inflammation and oxidative stress. Male Wistar rats were treated with the thiol-modifying agent diethylmaleate (DEM) to induce oxidative stress and rendered endotoxaemic by LPS injection. Human colonic biopsies and the human colon carcinoma cell line DLD-1 were treated with DEM and the lipid peroxidation end-product 4-hydroxynonenal to induce oxidative stress and exposed to cytokine mix (CM) to mimic inflammation. In some experiments, cells were incubated with 250-400 ppm CO prior to and during stimulation with CM. HO-1 and iNOS expression was evaluated by RT-PCR, western blotting, and immunohistology. NF-kappaB activation was evaluated by EMSA. LPS induced iNOS but not HO-1 in epithelial cells of the ileum and colon. Oxidative stress strongly induced HO-1 in epithelial and inflammatory cells. Combined oxidative stress and endotoxaemia decreased iNOS expression but strongly induced HO-1 expression. Similarly, CM induced iNOS but not HO-1 in colonic biopsies and DLD-1 cells. Oxidative stress prevented iNOS induction in an NF-kappaB-dependent manner but increased HO-1 expression in CM-exposed DLD-1 cells. CO inhibited iNOS mRNA induction in CM-stimulated DLD-1 cells. These data demonstrate opposite regulation of iNOS and HO-1 in intestinal epithelial cells in response to cytokine exposure and oxidative stress. These findings suggest that iNOS (NF-kappaB driven) and HO-1 (AP-1 driven) represent mutually exclusive survival mechanisms in intestinal epithelial cells.     

Involvement of gaseous low molecular monoxides in the cutaneous reverse passive Arthus reaction: cytoprotective action of carbon monoxide

The deposition of immune complexes (IC) induces an acute inflammatory response with tissue injury, for which the involvement of nitric oxide (NO) and carbon monoxide (CO) has been suggested. NO is induced by NO synthase (NOS) and CO is generated by haeme oxygenase (HO). Among HO isoenzymes, HO-1 is an induced type. To assess the role of NO and CO in the pathogenic process, the cutaneous reverse passive Arthus reaction was examined using NOS inhibitor, HO-1 stimulator and HO-1 inhibitor. To evaluate the reaction we considered oedema, tumour necrosis factor-alpha, interleukin-6, and neutrophil number. The values of these four parameters were significantly reduced in mice treated with HO-1 stimulator as compared with the positive control mice. Quite the reverse was observed in mice treated with HO-1 inhibitor. These results suggest that the HO-1/CO signalling pathway is a therapeutic target for human IC-mediated disease.     

神经型一氧化氮合酶与血红素氧合酶-2在应激后大鼠结肠的表达

目的探讨神经型一氧化氮合酶（nNOS）与血红素氧合酶-2（HO-2）在应激后大鼠结肠的表达.方法采用水浸-束缚应激（WRS）动物模型,用免疫组织化学SABC法检测nNOS和HO-2在大鼠结肠中的表达,并通过图像分析系统进行定量测定.结果对照组大鼠nNOS主要表达于结肠黏膜下神经丛和肌间神经丛的神经元,HO-2主要表达于结肠黏膜固有层黏膜肌、肌层环行肌及黏膜下层的血管内皮和平滑肌.应激组黏膜下神经丛和肌间神经丛的nNOS阳性神经元的平均灰度值较对照组明显增加,阳性神经元的平均数高于对照组,且在黏膜上皮细胞、固有层淋巴细胞也有nNOS表达;应激组HO-2阳性黏膜肌的平均灰度值较对照组增加,环行肌阳性单位（PU）明显高于对照组,在部分大肠腺也有HO-2表达.与应激组比较,应激＋L-NAME组的nNOS阳性神经元的平均灰度值减少,阳性神经元的平均数下降,应激＋ZnPP组HO-2阳性黏膜肌平均灰度值减少,环行肌PU下降.结论一氧化氮（NO）和一氧化碳（CO）均是结肠重要的气体信号分子和神经递质,两者在应激所致的结肠功能失调中可能具有协同作用.     

金纳多对内毒素诱导小鼠急性肺损伤保护作用机制的初步研究

目的：初步探讨银杏叶提取物金纳多（Ginaton）对内毒素（lipopolysaccharide, LPS）诱导小鼠的急性肺损伤(acute lung injury, ALI)保护作用的可能机制。方法：于小鼠腹腔注射LPS（10 mg/kg）复制ALI动物模型。将小鼠随机分为对照组、LPS组、Ginaton组和Ginaton＋LPS组。观察各组肺组织病理学改变,测量肺湿/干重比,支气管肺泡灌洗液蛋白含量及乳酸脱氢酶（lactate dehydrogenase, LDH）活性,测量丙二醛（malondialdehyde, MDA）、一氧化氮合酶（nitric oxide synthase, iNOS）和髓过氧化物（myeloperoxidase,MPO),免疫组织化学方法检测血红素加氧酶（heme oxygenase HO-1）及iNOS蛋白表达。结果： 金纳多可有效减轻LPS所致肺组织病理学变化,并降低肺湿/干重比和肺泡灌洗液中蛋白含量,降低肺泡灌洗液中LDH活性、肺组织MPO和iNOS活性,同时MDA和NO含量下降。免疫组织化学结果显示,LPS组iNOS表达上升（P＜0.01）,而血红素加氧酶（HO-1）蛋白表达未见明显变化;而预先给予Ginaton可显著提高HO-1的表达,降低iNOS的表达（P＜0.01）。结论：Ginaton可减轻LPS所致急性肺组织损伤,其机制可能与诱导HO-1的表达,下调iNOS的表达和活性有关。     

内源性CO对肺动脉高压大鼠NO体系的调节

目的:研究内源性血红素氧合酶(HO)/一氧化碳(CO)体系对低氧高二氧化碳性肺动脉高压大鼠一氧化氮合酶(NOS)/一氧化氮(NO)体系的调节作用, 以探讨一氧化碳对低氧高二氧化碳性肺动脉高压的作用机制。方法:将SD大鼠分为正常对照组, 4周低O₂高CO₂组, 4周低O₂高CO₂+血晶素组。测定各组大鼠肺动脉平均压(mPAP)、右心室/(左心室+室间隔)重量比, 检测动脉血、肺组织iNOS、cNOS、HO活性, 及CO、NO产生、释放的变化。结果:①低O₂高CO₂组mPAP、RV/(LV+S)显著高于对照组及血晶素组(P＜0.01)。②低O₂高CO₂组全血CO含量、血浆及肺组织匀浆血红素氧合酶-1(HO-1)活性均显著高于对照组(P＜0.01), 血晶素组大鼠血CO含量、血浆及肺组织匀浆HO-1活性进一步高于低O₂高CO₂组(P＜0.01)。③低O₂高CO₂组血浆及肺组织匀浆NO含量均显著低于对照组(P＜0.01), 血晶素组大鼠血浆及肺组织匀浆NO含量均显著高于低O₂高CO₂组(P＜0.01)。④低O₂高CO₂组血浆及肺组织匀浆iNOS活性均显著高于对照组(P＜0.01), 血浆及肺组织匀浆cNOS活性显著低于对照组(P＜0.01), 血晶素组大鼠血浆及肺组织匀浆iNOS活性均显著高于低O₂高CO₂组(P＜0.01), 血浆及肺组织匀浆cNOS活性与低O₂高CO₂组无明显差异。结论:HO/CO体系对NOS/NO体系具有调控作用, 慢性低O₂高CO₂情况下, 内源性一氧化碳体系可通过iNOS/NO途径对肺循环进行调节。     

Potential role of heme oxygenase-1 in the progression of rat adjuvant arthritis

Rat adjuvant arthritis is an experimental model widely used to evaluate etiopathogenetic mechanisms in chronic inflammation. We have examined the participation of heme oxygenase-1 (HO-1) in this experimental arthritis. In this study, an increased nitric oxide (NO) production in the paw preceded the upregulation of HO-1, whereas selective inhibition of inducible NO synthase (iNOS) after the onset of arthritis decreased HO-1 expression, suggesting that the induction of this enzyme may depend on NO produced by iNOS. Therapeutic administration of the HO-1 inhibitor tin protoporphyrin IX was able to control the symptoms of arthritis. This agent significantly decreased leukocyte infiltration, hyperplastic synovitis, erosion of articular cartilage and osteolysis, as well as the production of inflammatory mediators. In this experimental model, HO-1 can be involved in vascular endothelial growth factor production and angiogenesis. These results support a role for HO-1 in mediating the progression of the disease in this model of chronic arthritis.     

Nitric oxide increases Wnt-induced secreted protein-1 (WISP-1/CCN4) expression and function in colitis

Nitric oxide (NO) derived from the inducible NO synthase (iNOS) is an important and complex mediator of inflammation in the intestine. Wnt-inducible secreted protein (WISP)-1 (CCN4), a member of the connective tissue growth factor family, is involved in tissue repair. We sought to determine the relationship between iNOS and WISP-1 in colitis. By analyzing human colonic biopsy samples, we showed that the expression of mRNA for both iNOS and WISP-1 was significantly higher in ulcerative colitis samples compared with control tissue. The upregulation of WISP-1 was positively correlated with iNOS expression in two models of colitis, induced by intrarectal trinitrobenzenesulfonic acid (TNBS) or occurring spontaneously in IL-10 deficient mice. Loss of iNOS, studied using iNOS^−/− mice in both TNBS-induced and IL-10^−/− colitis models, significantly attenuated the colitis-related WISP-1 increase. In human colonic epithelial cell lines, the NO donor, DETA-NONOate, elevated WISP-1 mRNA and protein expression through a β-catenin and CREB-dependent, but Wnt-1-independent, pathway. In addition, NO-induced WISP-1 directly induced secretion of soluble collagen in colonic fibroblast cells. NO increases WISP-1 expression both in vitro and in vivo, suggesting a new role for iNOS and NO in colitis.     

内源性血红素氧合酶-1/一氧化碳系统对球囊损伤后再狭窄的影响

目的: 探讨血红素氧合酶-1(HO-1)/一氧化碳(CO)系统对球囊损伤后再狭窄的影响及其可能的作用机制。方法: 家兔随机分为5组(各组10只):对照组、胆固醇组、血红素组、卟啉锌组和假手术组。对照组予普通饮食,其余4组喂饲含1.5%胆固醇饲料,血红素组和卟啉锌组同时分别予氯化血红素或锌原卟啉-9腹腔内注射,2周后实验组行颈总动脉球囊损伤术,术后继续原喂养给药8周。结果: 与对照组比较,胆固醇组颈动脉一氧化氮(NO)生成量、结构型一氧化氮合酶(cNOS)活性显著降低,而CO生成量、HO-1 mRNA和蛋白表达显著增加,内膜面积和内膜/中膜面积比值增大,均P<0.01。与胆固醇组比较,氯化血红素干预显著增高HO-1 mRNA和蛋白表达,增加CO生成量,同时显著降低ET-1 mRNA和蛋白表达,减小内膜面积和内膜/中膜面积比值,均P<0.01;锌原卟啉-9显著降低HO-1 mRNA和蛋白表达,减少CO生成量,而ET-1 mRNA和蛋白表达显著增高,内膜面积和内膜/中膜面积比值增大,均P<0.01。结论: HO-1/CO系统通过代偿和调节NOS/NO系统以及降低ET-1表达,改善内皮功能和抑制内膜增殖,从而有效阻止再狭窄的发生发展。     

Inducible nitric oxide synthase expression in human colorectal cancer: correlation with tumor angiogenesis

To investigate the potential involvement of the nitric oxide (NO) pathway in colorectal carcinogenesis, we correlated the expression and the activity of inducible nitric oxide synthase (iNOS) with the degree of tumor angiogenesis in human colorectal cancer. Tumor samples and adjacent normal mucosa were obtained from 46 surgical specimens. Immunohistochemical expression of iNOS, vascular endothelial growth factor (VEGF), and CD31 was analyzed on paraffin-embedded tissue sections. iNOS activity and cyclic GMP levels were assessed by specific biochemical assays. iNOS protein expression was determined by Western blot analysis. iNOS and VEGF mRNA levels were evaluated using Northern blot analysis. Both iNOS and VEGF expressions correlated significantly with intratumor microvessel density (r(s) = 0.31, P = 0.02 and r(s) = 0.67, P < 0.0001, respectively). A significant correlation was also found between iNOS and VEGF expression (P = 0.001). iNOS activity and cyclic GMP production were significantly higher in the cancer specimens than in the normal mucosa (P < 0.0001 and P < 0.0001, respectively), as well as in metastatic tumors than in nonmetastatic ones (P = 0.002 and P = 0.04, respectively). Western and Northern blot analyses confirmed the up-regulation of the iNOS protein and gene in the tumor specimens as compared with normal mucosa. NO seems to play a role in colorectal cancer growth by promoting tumor angiogenesis.