内皮素，一氧化氮在内毒素血症大鼠胃粘膜损伤中的作用

目的：观察内皮素－1（ET－1）、一氧化氮（NO）在内毒素血症胃粘膜扣伤中的作用。方法：应用内毒素血症胃粘膜损伤模型分别观察血浆、胃粘膜中ET－1、NO含量变化,以及胃粘膜血流（GMBF）、胃粘膜损伤面积的变化。结果：内毒素血症时ET－1含量增加、NO含量减少,特异性内皮素受体ETAR阻滞剂（BQ123）、NO前体L－精氨酸（L－Arg）能减轻内毒素血症时胃粘膜损伤的程度。一氧化氮合酶阻滞剂N^G－硝基－L－精氨酸甲酯（L－NAME）加重了该模型胃粘膜的损伤。结论：内源性ET－1／NO失衡参与了内毒素血症时胃粘膜损伤病理过程。纠正内源性ET－1／NO失衡,通过改善了GMBF,减轻胃粘膜损伤。     

左旋精氨酸抑制大鼠心脏移植术后移植物血管病的研究

目的探讨左旋精氨酸(L—Arg)预防和治疗心脏移植术后移植物血管病的作用。方法建立大鼠异位心脏移植动物模型，观察给与L—Arg、一氧化氮合酶(NOS)抑制药物左旋精氨酸甲酯(L—NAME)后不同时间移植心脏冠状血管的改变。结果L—Arg组大鼠无移植物血管病(CAV)的形成和一氧化氮(NO)能大量合成，L—NAME组大鼠有CAV形成。结论NOS抑制药物L—NAME加重移植后移植物血管病病变，L—Arg可以预防和减轻移植后移植物血管病的病变，NO具有抑制新生内膜形成的作用。     

奥美拉唑对大鼠胃粘膜保护作用的研究

目的：探讨奥美拉唑对大鼠胃粘膜的保护作用。方法：在乙醇诱导大鼠胃粘膜损伤前，预先给予奥美拉唑、L－硝基－精氨酸甲酯（L－NAME）静脉注射。测定胃粘膜血流量（GMBF）、胃液pH和胃粘膜NO2^-/NO3^-含量，并观察胃粘膜损伤指数（Ulcer index ,UI)、溃疡坏死组织和中性粒细胞浸润严重程度的变化。结果：与模型损伤组比，奥美拉唑组大鼠UI明显降低（P＜0．01），溃疡坏死组织和中性粒细胞浸润程度明显减轻（P＜0．01）。预先用L－NAME处理后，奥美拉唑保护胃粘膜损伤的作用明显减弱。静脉注射奥美拉唑，可增加GMBF和胃粘NO2^-/NO3^－含量，L－NAME可逆转这种作用，但对奥美拉唑抑制酸分泌作用无明显影响。结论：奥美拉唑对大鼠胃粘膜具有重要的保护作用，一氧化氮介导了这种作用。     

左旋哨基精氨酸甲基酯对大鼠食管静脉曲张影响的酶组化研究

目的：探讨一氧化氮（NO）在食管静脉曲张发生机制中的作用,初步观察使用一氧化氮合酶（NOS）抑制剂治疗食管静脉曲张的可能性。方法：采用NADPH－d黄递酶组化染色与图像分析方法,观察NOS抑制剂左旋肖基精氨酸甲基酯（L－NAME）灌胃给药对食管静脉曲张大鼠食管壁组织学改变及NOS表达平均光密度值的影响。结果：模型组食管、粘膜下静脉壁及食管浆膜外静脉壁粘膜上皮NOS表达较假手术组增多,给予L－NAME后,食管壁NOS表达显著下调（P＜0．01）,L－NAME组10只大鼠中7只食管浆膜外静脉和粘膜下静脉迂曲扩张情况较模型组减轻。结论;大鼠食管静脉曲张的发病机制中有NO的参与;L－NAME对大鼠食管静脉曲张具有一定保护作用。     

β肾上腺素受体与左旋精氨酸/一氧化氮通路

自从发现血管内皮舒张因子 (EDRF)即一氧化氮(NO)后 ,其生物学作用引起众多学者关注。研究表明 :β肾上腺素受体 (β- AR)激活与左旋精氨酸 /一氧化氮 (L- Arg/ NO)通路存在密切关系。本文就这一关系的研究进展及其病理意义作一综述。1　 L- Arg/ NO系统体内许多细胞有 L- Arg/ NO合成通路 ,NO合成的底物是 L- Arg和氧 ,L- Arg作为 NO的前体物有高度的立体异构专一性。一氧化氮合酶 (NOS)是这一反应的唯一限速酶 ,产物是 NO与 L-瓜氨酸 (L -citrulline,L- Citn)。合成的 NO迅速扩散到邻近细胞 ,激活细胞内鸟苷酸环化酶 (GC…     

左旋精氨酸：一氧化氮通路与高血压

左旋精氨酸：一氧化氮通路与高血压成都市第三人民医院张大红刘晓平综述燕纯伯吴发琼审校左旋精氨酸（Ｌ－Ａｒｇ）在一氧化氮合酶（ＮＯｓｙｎｔｈｅｔａｓｅ，ＮＯＳ）的催化作用下生成一氧化氮（ＮＯ）这一生化过程，其英文名称为：Ｌ－ａｒｇｉｎｉｎｅ－ＮＯｐａｔｈ...     

左旋精氨酸—氧化氮途径与临床

左旋精氨酸（Ｌ－ａｒｇｉｎｉｎｅ，Ｌ－Ａｒｇ）通过一组酶的作用，合成一氧化氮（ＮＯ），后者在体内发挥多种生理性和病理性作用，介导多种临床疾病的发病机理，正在被生物学界与临床医学界关心与重视。Ｌ－Ａｒｇ－ＮＯ途径与ＮＯ的研究已涉及到临床各科领域。     

左旋精氨酸-一氧化氮途径与临床

左旋精氨酸（Ｌ－ａｒｇｉｎｉｎｅ，Ｌ－Ａｒｇ）通过一组酶的作用，合成一氧化氮（ｎｉｔｒｉｃｏｘｉｄｅ，Ｎｏ），后者在体内发挥多种生理性和病理性作用，介导多种临床疾病的发病机理，正在被生物学界与临床医学界关心与重视。Ｌ－Ａｒｇ－ＮＯ途径与ＮＯ的研究已涉及到临床各科领域。     

自发性高血压大鼠血清和心肌一氧化氮浓度的变化及L-精氨酸对其抑制作用

目的 :观察补充左旋精氨酸 4周后 12～ 13周龄自发性高血压大鼠 (SHR)血清和心肌组织一氧化氮(NO)浓度及血压的变化。方法 :通过腹腔注射补充NO合成前体———左旋精氨酸 (L Arg) 4周 ,硝酸还原酶法测定血清和心肌组织NO浓度 ;鼠尾压测量仪测量大鼠尾动脉的收缩压。结果 :治疗组SHR与对照组SHR相比心肌NO浓度降低 (P <0 .0 5 ) ,两组间血清NO浓度、血压差异无显著性意义 (P >0 .0 5 )。结论 :SHR 12～ 13周龄时体内NO呈代偿性地升高 ,通过腹腔注射慢性补充L Arg 4周使心肌组织NO浓度下降 ,但未能降低SHR已形成的高血压。     

左旋精氨酸对缺血—再灌注损伤肝脏的保护作用

目的探讨左旋精氨酸（L-arginine,L-Arg）对肝缺血－再灌注损伤（hepaticischemia-reperfusioninjury,HIRI）的防治作用及其机理。方法选择HIRI家兔及肝手术患者,观察一氧化氮水平、丙二醛浓度、血栓素B     

Influence of NG‐nitro‐L‐arginine methyl ester and L‐arginine on gastric mucosal tolerant cytoprotection under stress

OBJECTIVE : To determine the role of endogenous nitric oxide (NO) in gastric mucosal tolerant cytoprotection under stress and its possible mechanism. METHODS : Sprague–Dawley rats were exposed to repeated water immersion and restraint stress (WRS), during which N^G‐nitro‐L ‐arginine methyl ester (L ‐NAME), a non‐selective NO synthase inhibitor, and L ‐arginine (L ‐Arg), a substrate for NO synthesis, were administered to inhibit or promote the synthesis of endogenous NO, respectively. Gastric mucosal blood flow (GMBF) was measured with an LDF‐3 Flowmeter (Electronic Instrument Factory of Nankai University, Tianjin, China), the NO level in the gastric mucosa was monitored by the Griess reaction and gastric mucosal lesions were evaluated using the ulcer index (UI). The relationships between changes in GMBF, UI and NO content in the gastric mucosa were analyzed by linear correlation analysis. RESULTS : Repeated WRS induced gastric mucosal tolerant cytoprotection and this was accompanied by increased GMBF and NO levels in the gastric mucosa. Inhibition of endogenous NO synthesis by L ‐NAME worsened mucosal lesions induced by single WRS and, after repeated WRS, the adaptive incremence in GMBF was abolished and the NO content in the gastric mucosa was significantly reduced. In contrast, enhancement of endogenous NO synthesis by L ‐Arg attenuated mucosal erosions caused by single WRS. After repeated WRS, GMBF and the NO content in the mucosa increased gradually. Mucosal lesions were negligible after rats were exposed to the fourth WRS. CONCLUSIONS : During the tolerant cytoprotection, GMBF, UI and the NO content showed regular changes and there were good relationships between them. L ‐NAME and L ‐Arg changed the levels of endogenous NO, which, accordingly, affected GMBF and the gastric tolerance. By regulating GMBF, endogenous NO may play an important role in the gastric mucosal tolerant cytoprotection under stress. Inhibition of the synthesis of NO delayed the induction of tolerant cytoprotection, whereas increased NO synthesis promoted cytoprotection.     

GABAergic Mechanisms of Gastroprotection in the Rat: Role of Sensory Neurons, Prostaglandins, and Nitric Oxide

gamma-Aminobutyric acid (GABA) is a neurotransmitter found in both the central and the peripheral nervous systems including the gastrointestinal tract. The aims of the present studies were to examine mechanisms by which GABA exerts gastroprotective effects against ethanol- and water-restraint stress (WRS)-induced gastric mucosal injury in the rat. GABA, administered intragastrically (400 mg/kg), induced gastroprotection against ethanol and WRS by activating gastric sensory neurons to release calcitonin gene-related peptide (CGRP) and promote nitric oxide (NO) synthesis and release. Furthermore, these protective effects of GABA were associated with an increase in gastric mucosal blood flow (GMBF) that was dependent on sensory neuron and NO systems. GABA-mediated protection involved GABAA receptor activation and prostaglandin generation. In conclusion, intraluminal GABA protects the stomach against ethanol- and WRS-induced injury by mechanisms which involve sensory neuron/CGRP/NO pathways and increases in GMBF and prostaglandin generation.     

Role of TFF in healing of stress-induced gastric lesions

AIM: To determine the changes of pS2 and ITF of TFF expression in gastric mucosa and the effect on ulcer healing of pS2, ITF to Water-immersion and restraint stress (WRS)in rats.METHODS: Wistar rats were exposed to single or repeated WRS for 4 h every other day for up to 6 days. Gastric mucosal blood flow (GMBF) was measured by LDF-3 flowmeter and the extent of gastric mucosal lesions were evaluated grossly and histologically. Expression of pS2 and ITF mRNA was determined by RT-PCR. Immunohistochemistry was used to further detect the expression of pS2 and ITF.RESULTS: WRS applied once produced numerous gastric mucosal erosions, but the number of these lesions gradually declined and GMBF restored at 2, 4, 8 h after stress. The area of gastric mucosal lesion was reduced by 64.9 % and GMBF was increased by 89.8 % at 8 h. The healing of stress-induced ulcerations was accompanied by increased expression of pS2 (0.51±0.14 vs0.77±0.11, P＜0.01) and ITF (0.022±0.001 vs 0.177±0.010, P＜0.01). The results were demonstrated further by immunohistochemistry of pS2(0.95±0.11 vs1.41±0.04, P＜0.01) and ITF (0.134±0.001 vs 0.253±0.01,P＜0.01). With repeated WRS, adaptation to this WRS developed, the area of gastric mucosal lesions was reduced by 22.0 % after four consecutive WRS. This adaptation to WRS was accompanied by increased GMBF (being increased by 94.2 %), active cell proliferation in the neck region of gastric glands, and increased expression of pS2 (0.37±0.02 vs 0.77±0.01, P＜0.01) and ITF (0.040±0.001 vs0.372±0.010, P＜0.01). The result was demonstrated further by immunohistochemistry of pS2 (0.55±0.04 vs 2.46±0.08, P＜0.01) and ITF (0.134±0.001 vs0.354±0.070,P＜0.01).CONCLUSION: TFF may not only participate in the early phase of epithelial repair known as restitution(maked by increased cell migration),but also play an important role in the subsequent, protracted phase of glandular renewal(made by cell proliferation).     

应激状态下大鼠胃黏膜组织中内皮素-1A受体mRNA的表达及其意义

应激性溃疡(SU)是危重疾病的常见严重并发症,其发生机制尚不清楚。研究表明内源性缩血管因子内皮素(ET)-1与SU密切相关,而关于其受体表达在SU发生中作用的研究尚少。目的:探讨ET-1A受体(ETAR)mRNA表达在SU发生中的作用和意义。方法:以冷束缚应激(CRS)制备大鼠胃溃疡模型,应激前和应激1 h、3 h、6 h、9 h、12 h后分别采用放射免疫测定、逆转录聚合酶链反应(RT-PCR)和斑点杂交等方法,动态检测血浆和胃黏膜组织中的ET-1和胃黏膜组织中的ETAR mRNA水平,同时检测胃黏膜血流量(GMBF)和溃疡指数(UI)等指标的变化情况。结果:与正常对照组相比,各应激组大鼠血浆和胃黏膜组织中的ET-1水平均显著升高(P<0.05),GMBF显著下降(P<0.01),UI显著增加(P<0.01);胃黏膜组织中的ET-1水平与UI呈显著正相关(r=0.98,P<0.01),与GMBF呈显著负相关(r=-0.89,P<0.05),而血浆ET-1水平与GMBF、UI相关性不显著(r=-0.61,0.43,P>0.05)。GMBF与UI呈显著负相关(r=-0.98,P<0.01)。RT-PCR和斑点杂交显示各应激组大鼠胃黏膜组织中ETAR mRNA的表达水平较正常对照组显著升高(P<0.01),并与胃黏膜组织中的ET-1水平和UI呈显著正相关(r=0.93,0.95,P<0.01)。结论:在CRS诱发大鼠急性胃黏膜损伤的过程中,胃黏膜组织可显著增加ET-1的合成分泌和ETAR mRNA的     

Gastric mucosal blood flow response to stress in streptozotocin diabetic rats: Regulatory role of nitric oxide

To investigate cytoprotection against mucosal injuries of the stomach in patients with diabetes, we investigated gastric mucosal blood flow (GMBF), its response to a burn stress, and the involvement of nitric oxide (NO) in streptozotocin (STZ) diabetic rats. GMBF was measured by laser-Doppler velocimetry (LDV) and by the hydrogen gas clearance technique (HGC). The steady-state GMBF of STZ rats decreased according to the duration of diabetes, and insulin treatment blocked this decrease. Burn stress caused a rapid decrease in the GMBF. Reduction of the GMBF and gastric mucosal leakage of Evans blue (EB) after the burn stress were greater in the STZ rats than in the controls, but insulin treatment completely blocked this increase in EB leakage in the STZ rats. There was a significant negative correlation between the percent GMBF 3 h after the burn stress and EB leakage at the same time point. In the controls and the insulin-treated STZ rats, N-nitro-l-arginine (l-NNA) an NO synthase inhibitor, enhanced the decrease in postburn GMBF and EB leakage, but was without effect in the STZ rats. These results suggest that NO may be involved in the regulation of GMBF, and that persistent hyperglycemia may impair this regulation. These findings suggest that patients with diabetes have reduced cytoprotection against a variety of gastric mucosal injuries.     

Grapefruit-seed extract attenuates ethanol-and stress-induced gastric lesions via activation of prostaglandin, nitric oxide and sensory nerve pathways

AIM: Grapefruit-seed extract (GSE) containing flavonoids, possesses antibacterial and antioxidative properties but whether it influences the gastric defense mechanism and gastroprotection against ethanol- and stress-induced gastric lesions remains unknown. METHODS: We compared the effects of GSE on gastric mucosal lesions induced in rats by topical application of 100% ethanol or 3.5 h of water immersion and restraint stress (WRS) with or without (A) inhibition of cyclooxygenase (COX)-1 activity by indomethacin and rofecoxib, the selective COX-2 inhibitor, (B) suppression of NO-synthase with L-NNA (20 mg/kg ip), and (C) inactivation by capsaicin (125 mg/kg sc) of sensory nerves with or without intragastric (ig) pretreatment with GSE applied 30 min prior to ethanol or WRS. One hour after ethanol and 3.5 h after the end of WRS, the number and area of gastric lesions were measured by planimetry, the gastric blood flow (GBF) was assessed by H2-gas clearance technique and plasma gastrin levels and the gastric mucosal generation of PGE2, superoxide dismutase (SOD) activity and malonyldialdehyde (MDA) concentration, as an index of lipid peroxidation were determined. RESULTS: Ethanol and WRS caused gastric lesions accompanied by the significant fall in the GBF and SOD activity and the rise in the mucosal MDA content. Pretreatment with GSE (8-64 mg/kg i g) dose-dependently attenuated gastric lesions induced by 100% ethanol and WRS; the dose reducing these lesions by 50% (ID50) was 25 and 36 mg/kg, respectively, and this protective effect was similar to that obtained with methyl PGE2 analog (5 μg/kg i g). GSE significantly raised the GBF, mucosal generation of PGE2, SOD activity and plasma gastrin levels while attenuating MDA content. Inhibition of PGE2 generation with indomethacin or rofecoxib and suppression of NO synthase by L-NNA or capsaicin denervation reversed the GSE-induced protection and the accompanying hyperemia. Co-treatment of exogenous calcitonine gene-related peptide (CGRP) with GSE restored the protection and accompanying hyperemic effects of GSE in rats with capsaicin denervation. CONCLUSION: GSE exerts a potent gastroprotective activity against ethanol and WRS-induced gastric lesions via an increase in endogenous PG generation, suppression of lipid peroxidation and hyperemia possibly mediated by NO and CGRP released from sensory nerves.     

Nitric oxide releasing aspirin protects the gastric mucosa against stress and promotes healing of stress-induced gastric mucosal damage: role of heat shock protein 70

BACKGROUND/AIM: Nitric oxide (NO) releasing nonsteroidal anti-inflammatory drugs do not cause gastric mucosal damage, despite inhibition of the cyclooxygenase activity to a similar extent as conventional nonsteroidal anti-inflammatory drugs that induce such damage. We compared the effects of native aspirin (ASA) with those of NO-releasing ASA (NO-ASA) on the development and healing of acute gastric lesions induced by water immersion and restraint stress (WRS) and the mucosal expression of heat shock protein 70 (HSP70). METHODS: Wistar rats received: (1). vehicle; (2). ASA (40 mg/kg i.g), and (3). NO-ASA (2.5-40 mg/kg i.g.), followed 0.5 h later by 3.5 h of WRS with or without glyceryl trinitrate, the donor of NO, and carboxy-PTIO, a NO scavenger. Healing of WRS lesions was assessed 0-24 h after termination of WRS. Number of gastric lesions, gastric mucosal blood flow (GBF), malondialdehyde (MDA) content, and RT-PCR expression of HSP70 mRNA were determined. RESULTS: WRS caused typical bleeding erosions that were aggravated by aspirin and this was accompanied by a fall in the GBF and a significant rise in the mucosal MDA concentrations. In contrast, NO-ASA, which raised significantly the luminal content of NO(x), reduced number of WRS lesions and mucosal MDA levels while increasing significantly the GBF. These protective and hyperemic effects of NO-ASA against WRS lesions were mimicked by addition of glyceryl trinitrate to native ASA and significantly attenuated by carboxy-PTIO added to NO-ASA. HSP70 mRNA was significantly upregulated by WRS, and this was significantly attenuated by ASA, but not by NO-ASA. NO-ASA decreased significantly the MDA content and induced overexpression of HSP70 mRNA during healing of WRS lesions. CONCLUSION: NO-ASA exhibits mucosal protective and healing effects against WRS-induced gastric lesions due to the release of NO, which induces gastric hyperemia, and the attenuation of lipid peroxidation and counteracts the inhibition of HSP70 expression induced by native ASA.     

Monochloramine impairs mucosal blood flow response and healing of gastric lesions in rats: relation to capsaicin-sensitive sensory neurons

AIMS:We examined the effects of monochloramine (NH2Cl) on the gastric mucosal blood flow (GMBF) response and the healing of ethanol-induced gastric lesions in rats. METHODS: Rats fasted for 18 h were given the 99% ethanol p.o. for induction of gastric lesions, and were fed normally from 1 h later onwards. Monochloramine, at non-ulcerogenic doses (5 to approximately 20 mmol/L), was given p.o. twice daily for 7 days, starting 2 h after ethanol treatment. RESULTS: Gastric lesions caused by ethanol healed almost completely within 7 days with re-epithelialization. The repeated administration of NH2Cl significantly delayed the healing of ethanol-induced gastric lesions in a dose-dependent manner. The damaged mucosa showed a marked rise in H+ permeability, resulting in luminal acid loss, but this process was accompanied by an increase of mucosal blood flow. Monochloramine did not affect the increased mucosal H+ permeability observed in the stomach after damage by ethanol, but significantly inhibited the mucosal hyperemic response associated with luminal acid loss. Prior exposure of the mucosa to NH2Cl (20 mmol/L) did not affect the gastric hyperemic response caused by mucosal application of misoprostol (a prostaglandin E1 derivative) or NOR-3 (a nitric oxide donor), but totally attenuated the increase of GMBF in response to intragastric capsaicin. Impaired healing and GMBF responses were also observed in rats following chemical ablation of capsaicin-sensitive sensory neurons. CONCLUSIONS: These results suggest that NH2Cl impaired the healing of acute gastric mucosal lesions at low concentrations, and this action may be attributable, at least partly, to the impairment of gastric hyperemic response caused by the dysfunction of capsaicin-sensitive sensory neurons.