神经元型一氧化氮合酶反义寡脱氧核苷酸抑制大鼠吗啡戒断症状

目的　观察鞘内或侧脑室注射神经元型一氧化氮合酶 (nNOS)反义寡脱氧核苷酸对大鼠吗啡戒断症状的影响。方法　根据基因结构设计nNOS或eNOS反义寡脱氧核苷酸片段 ,用逆转录聚合酶链反应 (RT PCR)测定nNOSmR NA表达。结果　吗啡依赖大鼠在纳洛酮激发前 2 4h鞘内注射nNOS反义寡脱氧核苷酸抑制所有大鼠吗啡戒断症状如湿狗摇动、扭体及激惹、腹泻、体重减少、咬牙和流涎。eNOS反义寡脱氧核苷酸对吗啡戒断症状总评分值没有影响 ,但减少腹泻、体重减轻值和咬牙等评分值。侧脑室注射nNOS反义寡脱氧核苷酸减少吗啡戒断症状 ,eNOS反义寡脱氧核苷酸对吗啡戒断症状没有影响。鞘内注射nNOS反义寡脱氧核苷酸后脊髓nNOSmRNA的相对表达几乎消失 ,iNOS的表达增加 ;而eNOS反义寡脱氧核苷酸处理后对nNOS和iNOS的表达没有影响。结论　nNOS基因表达介导了吗啡戒断反应过程 ,抑制nNOS基因表达可增加脊髓i NOS基因的表达。     

Endothelium-independent relaxation of aortic rings by the nitric oxide synthase inhibitor diphenyleneiodonium

1. The flavoprotein binder diphenyleneiodonium (DPI) is a potent, irreversible inhibitor of nitric oxide synthase (NOS), but produces only a transient pressor response following systemic administration to animals, despite evidence of persistent NOS inhibition. To characterize further the effects of DPI on vascular tone, isometric tension was recorded from rat isolated aortic rings mounted between steel wires in an organ bath.
2. The NOS inhibitor N^G-nitro-L-arginine methyl ester (L-NAME, 1 mM) initiated an additional contraction of prostaglandin F_2α-preconstricted rings with endothelium which was sustained throughout the period of L-NAME exposure (+234±39% at 15 min). In contrast, addition of DPI (5 μM) to rings with endothelium produced a transient initial contraction (+111±27% at 2 min) followed by a more sustained relaxation (−27±19% at 15 min, P<0.001 vs L-NAME).
3. The contraction to DPI was also observed in rings without endothelium, was abolished by L-NAME pretreatment, and was unaffected by the α-adrenoreceptor inhibitor prazosin. Relaxation in response to DPI was not inhibited by endothelium removal or by pretreatment with either L-NAME or with the ATP-sensitive potassium channel blocker glibenclamide.
4. The endothelium-independent relaxation to DPI was inhibited at 23°C and its time course was delayed by pretreatment with the guanylate cyclase inhibitor methylene blue.
5. Thus, in addition to a transient initial contraction due to NOS inhibition, DPI produces an endothelium-independent, temperature-dependent relaxation which appears in part due to activation of guanylate cyclase. This relaxant effect of DPI may explain the transient nature of its pressor effect in vivo despite sustained NOS inhibition.

     

吗啡依赖及戒断大鼠脊髓和脑干中一氧化氮合酶基因的表达

目的　观察吗啡依赖或吗啡戒断大鼠脊髓和脑干中一氧化氮合酶 (NOS)基因表达的变化。方法　以 β actin为内参照 ,用逆转录聚合酶链反应 (RT PCR)测定NOSmRNA的表达水平。结果　吗啡依赖大鼠脊髓和脑干NOS表达水平较正常对照大鼠降低 ,纳洛酮 ( 4mg·kg-1,ip)激发大鼠吗啡戒断症状 1h后脊髓和脑干中NOS表达水平明显升高 ,戒断 2h和 4h后NOS基因表达较 1h组减少。NOS抑制剂L N 硝基精氨酸甲酯 (L NAME ,10mg·kg-1)处理后大鼠吗啡戒断症状减少 ,同时脊髓和脑干的NOS基因表达水平较戒断 1h组明显降低。甲基东莨菪碱 ( 0 5mg·kg-1)处理组脊髓和脑干中NOS表达水平较戒断 1h组明显降低 ;选择性毒蕈碱受体M1拮抗剂 pirenzepine( 10mg·kg-1)处理组动物脊髓中NOS表达水平较戒断 1h组降低 ,而脑干中NOS表达水平没有改变 ;NMDA受体拮抗剂MK 80 1( 0 12 5mg·kg-1)处理后脊髓和脑干中NOS表达水平较戒断 1h组没有差异。结论　吗啡慢性处理后脊髓和脑干中NOSmR NA水平降低 ,抑制内源性NO生成和阻断毒蕈碱受体可以减少吗啡戒断所引起脊髓和脑干中NOS基因的表达     

Role of nitric oxide in mediating vasodilator responses to opioid peptides in the rat

1. Endomorphins 1 and 2, endogenous ligands for the mu-opioid receptor, and nociceptin (orphanin FQ; OFQ), an endogenous ligand for the ORL1 receptor, have vasodilator activity in the vascular bed of the hindquarters of the rat. In the present study, the role of nitric oxide (NO), vasodilator prostaglandins and the opening of KATP channels in mediating vasodilator responses to these novel agonists was investigated in the rat. 2. Under constant-flow conditions, injections of endomorphins 1 and 2, PL017 ([N-MePhe3,D-Pro4]-morphiceptin), nociceptin and Tyr-D-Ala-Gly-MePhe-Gly(ol)-enkephalin (DAMGO) produced dose-dependent decreases in hindquarters perfusion pressure. Vasodilator responses to endomorphin 1 and 2, acetylcholine and adrenomedullin, were attenuated by the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) at a time when vasodilator responses to nociceptin, adrenomedullin and the NO donor diethylamine/NO were not altered. 3. Vasodilator responses to endomorphins 1 and 2, nociceptin, PL017 and DAMGO were not altered after administration of sodium meclofenamate at a time when vasodilator responses to arachidonic acid were reduced significantly or after administration of U-37883A at a time when vasodilator responses to levcromakalim were reduced significantly. 4. The results of these studies indicate that vasodilator responses to endomorphins 1 and 2, PL017 and DAMGO are mediated, in large part, by the release of NO, whereas vasodilator responses to nociceptin are mediated by an L-NAME-insensitive mechanism. Moreover, these results demonstrate that the vasodilator responses to these peptides are not due to the release of vasodilator prostaglandins or the opening of KATP channels in the hindquarters vascular bed of the rat.     

高压氧对脑梗死后血清一氧化氮和一氧化氮合酶含量的影响

目的 研究高压氧对脑梗死后血清一氧化氮、一氧化氮合酶含量的影响。方法 将脑梗死患者分为高压氧治疗组和非高压氧治疗组,观察不同病期血清一氧化氮、一氧化氮合酶含量的变化,并与正常对照组进行比较。结果 高压氧治疗组一氧化氮含量较非高压氧治疗组上升快,在治疗后15天恢复正常,但在一疗程高压氧治疗结束后,却又有所下降;一氧化氮合酶含量在治疗后均有上升,未能恢复到正常水平,两组之间无差异。结论 高压氧通过提高NO的含量,减轻缺血区脑组织的损伤,改善脑血循环;高压氧对NOS有一定影响,但作用不大;应适当延长高压氧疗程,尽可能缓解因NOS含量下降所造成的NO释放量不足。     

Effects of chronic inhibition of nitric oxide synthase in the genetically hypertensive rat

1. The effects of graded inhibition of nitric oxide synthase (NOS) on blood pressure in the genetically hypertensive (GH) rat strain and NOS activity in regions of the brain (cerebellum, striatum, hippocampus, frontal cortex and medulla oblongata) as a measure of body NOS inhibition were studied. 2. Male GH and normotensive (N) rats (n = 7-10 per group) were given N(G)-nitro-L-arginine methyl ester (L-NAME; 2, 5, 10 or 20 mg/kg per day in drinking water) from age 7 weeks. Age- and weight-matched controls received water only. Systolic blood pressure (SBP) was measured weekly by the tail-cuff method from age 6 weeks. By age 10 weeks, rats were killed and NOS activity was measured. 3. Some GH rats that received over 5 mg/kg per day L-NAME developed stroke-like symptoms and were killed before the end of the treatment period. 4. No difference in NOS activity was found between untreated N and GH strains but, in those that received treatment, a graded inhibition was observed with increasing L-NAME dose levels. The frontal cortex in the GH strain given 20 mg/kg per day L-NAME had NOS inhibition of 90% where the N strain had 73% inhibition. Similar results were seen in the other areas of the brain. 5. Left ventricular mass, weight related, was significantly greater in the GH compared with N and was further elevated by treatment with L-NAME. 6. The SBP at 10 weeks was significantly elevated in GH rats by NOS inhibition with L-NAME in a dose-dependent manner; 25% for 2 mg/kg per day, 31% for 20 mg/kg per day (P < 0.001). There was a non-significant increase in BP in the N-treated groups (average change of 7.5%). 7. Nitric oxide synthase inhibition causing increased SBP in GH rats suggests an abnormality in the nitric oxide-L-arginine pathway in this strain.     

硫化氢下调大鼠主动脉L-精氨酸/一氧化氮合酶/一氧化氮通路

目的观察H2S对血管L-精氨酸/一氧化氮(L-Arg/NO)通路的影响以探讨H2S和NO这两种气体信号分子间的相互作用。方法离体孵育大鼠主动脉薄片,加入H2S供体NaHS(10-7~10-4mol.L-1)孵育4 h,及50μmol.L-1NaHS分别孵育2、4和6 h。采用G re iss法测定血管亚硝酸盐含量;同位素示踪法检测血管组织一氧化氮合酶(NOS)活性及L-Arg转运,RT-PCR检测eNOS、CAT1基因表达。结果一次性给予50μmol.L-1NaHS,孵育2 h,孵育液中NO2-含量比对照组低62%,血管NOS活性下降48%,L-Arg转运减少50%(P<0.01);孵育6 h,NO2-含量比对照组低19%(P<0.05),而NOS活性和L-Arg转运已基本恢复(P>0.05)。NaHS(10-7~10-4mol.L-1),呈浓度依赖的抑制了L-Arg/NOS/NO通路,IC50分别为0.499、3.198及3.927μmol.L-1(P<0.01);而给予50μmol.L-1NaHS后,eNOS和CAT-1A的mRNA表达分别减少34.3%和55.1%(P<0.01)。结论H2S通过抑制血管组织L-Arg转运和NOS活性和基因表达,下调L-Arg/NOS/NO通路,从而减少血管NO生成。     

一氧化氮合酶抑制剂的研究进展

一氧化氮（ｎｉｔｒｉｃｏｘｉｄｅ,ＮＯ）是一种能调节细胞多种功能的信息分子,它参与心血管、外周和中枢神经以及免疫等系统生理过程和生物信号的调节。体内组织中的ＮＯ由ＮＯ合酶（Ｎｉｔｒｉｃｏｘｉｄｅｓｙｎｔｈａｓｅ,ＮＯＳ）催化左旋精氨酸而合成,合成后的ＮＯ迅速跨膜扩散释放。各种调节ＮＯ释放的因素均作用于ＮＯＳ催化的化学反应过程,而体内影响该反应的ＮＯＳ在各组织的表达不同。特异性ＮＯＳ抑制剂通过调控ＮＯ的合成,对ＮＯＳ表达相关的各种疾病的预防和治疗具有重要的临床意义。本文对近年来ＮＯＳ抑制剂的研究进展作一概述。     

罗红霉素通过诱导型一氧化氮合酶/一氧化氮途径抑制哮喘大鼠气道炎症

目的探讨罗红霉素对哮喘大鼠支气管诱导型一氧化氮合酶(iNOS)及一氧化氮(NO)的影响。方法24只成年哮喘大鼠随机分成对照组、哮喘组以及罗红霉素组。对支气管肺泡灌洗液(BALF)细胞总数及嗜酸性粒细胞计数,免疫组织化学检测大鼠支气管上皮细胞iNOS蛋白表达,RT-PCR检测肺组织iNOS mRNA表达,分光光度计检测肺组织iNOS活性及NO含量。双抗体夹心法检测肺组织白细胞介素-4(IL-4)及干扰素-γ(IFN-γ)。结果哮喘组大鼠BALF细胞总数及嗜酸性粒细胞分类分别为(7.28±1.65)×108.L-1、(7.73±1.54)%,均高于对照组(3.76±0.97)×108.L-1、(1.27±0.60)%;罗红霉素组BALF细胞总数及嗜酸性粒细胞分类分别为(5.68±0.95)×108.L-1、(5.54±1.53)%,明显低于哮喘组,差异有统计学意义。哮喘组肺组织IL-4浓度、iNOS活性及NO含量高于对照组,罗红霉素组肺组织IL-4浓度、iNOS活性及NO含量低于哮喘组。哮喘组肺组织IFN-γ浓度低于对照组,罗红霉素组肺组织IFN-γ浓度高于哮喘组。哮喘大鼠支气管上皮细胞iNOS蛋白及肺组织iN-OSmRNA表达分布吸光度值分别为(0.25±0.06)、(0.52±0.14),较对照组[(0.14±0.05),(0.33±0.05)]明显增强;但罗红霉素组iNOS蛋白及mRNA表达为(0.15±0.03)、(0.35±0.07),均明显较哮喘组减弱。结论罗红霉素通过干预哮喘大鼠气道IL-4、IFN-γ以及iNOS/NO体系,抑制哮喘气道炎症反应。     

神经元型一氧化氮合酶在心脏功能调节中的作用

神经元型一氧化氮合酶(nNOS)不仅在神经细胞中表达,也存在于心肌细胞。生理状况下,nNOS源性的一氧化氮(NO)通过自分泌以负反馈的调节方式维持细胞内Ca2+浓度稳态,防止细胞内Ca2+浓度超载,对于维持正常的心功能具有重要意义。病理状况下,nNOS的活性发生明显变化,nNOS源性的NO可能参与了心脏疾病的发生和发展。     

布地奈德对哮喘大鼠中性粒细胞诱导型一氧化氮合酶表达的影响

目的：观察诱导型一氧化氮合酶（iNOS）蛋白在哮喘大鼠血中性粒细胞（PMN）中的表达,探讨PMN参与哮喘炎症的可能机制,并研究布地奈德的影响。方法：采用卵白蛋白（OVA）和Al（OH）3制备大鼠哮喘模型,分离纯化血PMN,免疫细胞化学法检测PMN中iNOS蛋白的表达水平,比色法测定支气管肺泡灌洗液（BALF）中NO浓度。结果：哮喘组大鼠PMN中iNOS蛋白的表达水平显著高于正常对照组（P〈0.01）,布地奈德治疗组PMN中iNOS蛋白的表达水平显著低于哮喘组（P〈0.01）;哮喘组支气管壁iNOS蛋白的表达水平显著高于正常对照组（P〈0.01）,布地奈德治疗组支气管壁iNOS蛋白的表达水平显著低于哮喘组且高于正常对照组（均P〈0.01）;哮喘组BALF中NO浓度显著高于正常对照组（P〈0.01）,布地奈德治疗组BALF中NO浓度显著低于哮喘组（P〈0.01）;PMN中iNOS蛋白的表达水平与BALF中NO浓度呈显著正相关（n=29,r=0.754,P〈0.01）;支气管壁iNOS蛋白的表达水平与BALF中NO浓度呈显著正相关（n=29,r=0.760,P〈0.01）。结论：哮喘大鼠PMN合成iN-OS蛋白的功能增加,PMN可能部分通过iNOS参与哮喘的发病,这种功能可以部分被布地奈德所抑制。     

一氧化氮合酶抑制剂氨基胍对脑缺血大鼠脑组织氨基酸含量的影响(英文)

目的　探讨氨基胍对大鼠脑缺血组织的保护作用及其作用机制。方法　采用线栓法复制大鼠中脑动脉梗死模型,缺血后给予氨基胍治疗。相应时间断头取脑,然后测定脑梗死体积、脑组织中氨基酸的含量。结果　脑梗死体积氨基胍组较缺血组明显缩小;缺血组比假手术组纹状体、海马、皮质中天门冬氨酸、谷氨酸、甘氨酸、GABA含量显著增加,给予氨基胍治疗后,天门冬氨酸、谷氨酸的含量明显降低,甘氨酸、GABA含量明显升高。结论　氨基胍降低脑组织中兴奋性氨基酸的含量,升高抑制性氨基酸的含量可能是保护脑缺血的重要机制     

戊四唑癫痫大鼠脑组织一氧化氮含量和一氧化氮合酶活性变化

探讨一氧化氮在戊四唑癫病发机制中的作用。方法每天注射戊四唑建立在鼠癫痫模型,测定癫病发作后大鼠大脑皮质,海马一氧化氮和一氧化氮合酶活性变化,结果癫痫发作后海马ＮＯ含量和ＮＯＳ活性显著升高,结 戊四唑诱导的癫痫中具有致痫性。     

香菇多糖对巨噬细胞一氧化氮和一氧化氮合酶活性的影响

目的研究香菇多糖(LTN)诱导巨噬细胞的一氧化氮(NO)生成和一氧化氮合酶(iNOS)的活性,探讨LTN的免疫调节作用机理.方法采用Griess反应和荧光法测定不同剂量的LTN作用小鼠腹腔巨噬细胞后NO的生成量和iNOS活性.观察mRNA转录抑制剂、蛋白质合成抑制剂和iNOS抑制剂对巨噬细胞NO的生成和iNOS活性的影响.结果LTN能使小鼠腹腔巨噬细胞NO生成增加,iNOS活性增高,并呈作用剂量依赖关系.3种抑制剂均能抑制LTN诱导的小鼠腹腔巨噬细胞N0的生成和iNOS活性.结论LTN能刺激小鼠腹腔巨噬细胞提高iNOS活性和NO的生成.提示LTN的免疫调节作用机制可能与LTN刺激巨噬细胞NO生成有关.     

Cardiovascular effects of chronic nitric oxide synthase inhibition in genetically hypertensive rats

1. The possible role of an endothelial defect in the hypertension of the New Zealand genetically hypertensive (GH) rat strain was assessed by examining cardiovascular responses to the nitric oxide synthase (NOS) inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) and the endothelium-dependent depressor agent acetylcholine (ACh). The vascular sensitivity of the hindquarter to nitric oxide (NO) was examined using the NO donor sodium nitroprusside (SNP). 2. NG-Nitro-L-arginine methyl ester (10 mg/kg per day in drinking water) was given to GH and normotensive (N) rats from age 7-9 weeks, with GH and N untreated control groups. Systolic blood pressure (tail-cuff) was monitored weekly from age 5-9 weeks. At age 9 weeks, pressure responses to various vasoactive agents were measured in vivo and in the rat isolated hindquarter. Left ventricular (LV) mass was measured at the time of death. 3. NG-Nitro-L-arginine methyl ester induced a greater hypertensive effect in GH (P < 0.001) compared with N (P < 0.05) rats and caused a significant increase in hindquarter perfusion pressure in GH rats only (P < 0.01). 4. Genetically hypertensive rats had LV hypertrophy that was exacerbated by L-NAME (P < 0.01). Left ventricular hypertrophy was not induced by L-NAME in N rats. 5. The normalized response to ACh did not differ between GH and N control rats and was unaffected by L-NAME treatment in vivo and in vitro except at the highest ACh dose (3 micrograms/kg) in GH hindquarters (P < 0.01). The response to SNP was similar in GH and N hindquarters and enhanced by L-NAME in GH (0.1 microgram; P < 0.05) and N rats (0.01 microgram, P < 0.01; 0.01 microgram, P < 0.001). 6. These results suggest that the L-arginine/NO system is not deficient in GH rats and that endothelial function in the GH hindquarter is preserved. They confirm that NO is involved in mediating blood pressure in GH and N rats and raise the possibility that a non-NO-mediated mechanism may underlie ACh-induced vasodilation in GH and N.     

神经节苷脂GM1对新生鼠缺血缺氧后NOS表达的影响

目的：探讨神经节苷酯GM1对新生儿缺氧缺血性脑病的保护作用及可能机理。方法：通过建立新生鼠缺氧缺血性脑病动物模型，观察缺血缺氧后不同时期脑组织的病理变化和一氧化氮合酶（NOS）表达，以及GM1对其影响。结果：GM1给药组脑组织损伤明显减轻，缺血缺氧可诱导脑组织中NOS表达水平上调，GM1部分地抑制了缺血缺氧后NOS的表达水平。结论：GM1对新生儿缺氧缺血性脑损伤具有一定程度的保护作用，其作用可能是通过部分抑制NOS的表达。     

五味子乙素对染矽尘大鼠肺组织一氧化氮水平和诱导型一氧化氮合酶mRNA表达动态变化的影响

目的观察五味子乙素(Sch-B)对染矽尘大鼠肺组织一氧化氮(NO)水平和诱导型一氧化氮合酶(iNOS)mRNA动态变化的影响。方法将96只大鼠随机分为对照组、染矽尘组、Sch-B组,每组32只,气管暴露法建立大鼠矽肺模型,造模后d 1开始灌胃给予Sch-B治疗,药物治疗3 d、7 d、14 d和28 d后,HE染色检测肺组织病理改变;硝酸还原酶法测肺组织NO含量;RT-PCR检测肺组织iNOS mRNA的表达。结果 HE染色显示Sch-B组大鼠肺损伤较染矽尘组明显减轻。NO含量和iNOS mRNA表达在染尘后各个时间点均较相应的对照组明显升高(P<0.01),其中NO含量在d 7时达到高峰后开始下降,iNOS mRNA的峰值出现在d 14。五味子组与染矽尘组相比,各时间点NO含量均明显降低(P<0.05或P<0.01),而iNOS mRNA表达仅在d 3和d 7时降低明显(P<0.05)。结论染矽尘大鼠肺组织存在着NO含量和iNOS mRNA的动态变化。Sch-B能减轻染矽尘大鼠肺组织的纤维化程度,其机制可能与染尘初期Sch-B降低iNOS mRNA转录水平,抑制NO炎症介质的合成与释放有关。     

Ethanol consumption increases the expression of endothelial nitric oxide synthase, inducible nitric oxide synthase and metalloproteinases in the rat kidney

Objectives The effects of longterm ethanol consumption on the levels of nitric oxide (NO) and the expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS) and metalloproteinase‐2 (MMP‐2) were studied in rat kidney. Methods Male Wistar rats were treated with 20% ethanol (v/v) for 6 weeks. Nitrite and nitrate generation was measured by chemiluminescence. Protein and mRNA levels of eNOS and iNOS were assessed by immunohistochemistry and quantitative real‐time polymerase chain reaction, respectively. MMP‐2 activity was determined by gelatin zymography. Histopathological changes in kidneys and indices of renal function (creatinine and urea) and tissue injury (mitochondrial respiration) were also investigated. Results Chronic ethanol consumption did not alter malondialdehyde levels in the kidney. Ethanol consumption induced a significant increase in renal nitrite and nitrate levels. Treatment with ethanol increased mRNA expression of both eNOS and iNOS. Immunohistochemical assays showed increased immunostaining for eNOS and iNOS after treatment with ethanol. Kidneys from ethanol‐treated rats showed increased activity of MMP‐2. Histopathological investigation of kidneys from ethanol‐treated animals revealed tubular necrosis. Indices of renal function and tissue injury were not altered in ethanol‐treated rats. Conclusions Ethanol consumption increased renal metalloproteinase expression/activity, which was accompanied by histopathological changes in the kidney and elevated NO generation. Since iNOS‐derived NO and MMPs contribute to progressive renal injury, the increased levels of NO and MMPs observed in ethanol‐treated rats might contribute to progressive renal damage.     

Effect of nitrovasodilators and inhibitors of nitric oxide synthase on ischaemic and reperfusion function of rat isolated hearts

1. The functional role of the nitric oxide (NO)/guanosine 3′:5′-cyclic monophosphate (cyclic GMP) pathway in experimental myocardial ischaemia and reperfusion was studied in rat isolated hearts.
2. Rat isolated hearts were perfused at constant pressure with Krebs-Henseleit buffer for 25 min (baseline), then made ischaemic by reducing coronary flow to 0.2 ml min⁻¹ for 25 or 40 min, and reperfused at constant pressure for 25 min. Drugs inhibiting or stimulating the NO/cyclic GMP pathway were infused during the ischaemic phase only. Ischaemic contracture, myocardial cyclic GMP and cyclic AMP levels during ischaemia, and recovery of reperfusion mechanical function were monitored.
3. At baseline, heart rate was 287±12 beats min⁻¹, coronary flow was 12.8±0.6 ml min⁻¹, left ventricular developed pressure (LVDevP) was 105±4 mmHg and left ventricular end-diastolic pressure 4.6±0.2 mmHg in vehicle-treated hearts (control; n=12). Baseline values were similar in all treatment groups (P>0.05).
4. In normoxic perfused hearts, 1 μM N^G-nitro-L-arginine (L-NOARG) significantly reduced coronary flow from 13.5±0.2 to 12.1±0.1 ml min⁻¹ (10%) and LVDevP from 97±1 to 92±1 mmHg (5%; P<0.05, n=5).
5. Ischaemic contracture was 46±2 mmHg, i.e. 44% of LVDevP in control hearts (n=12), unaffected by low concentrations of nitroprusside (1 and 10 μM) but reduced to ∼30 mmHg (∼25%) at higher concentrations (100 or 1000 μM; P<0.05 vs control, n=6). Conversely, the NO synthase inhibitor L-NOARG reduced contracture at 1 μM to 26±3 mmHg (23%), but increased it to 63±4 mmHg (59%) at 1000 μM (n=6). Dobutamine (10 μM) exacerbated ischaemic contracture (81±3 mmHg; n=7) and the cyclic GMP analogue Sp-8-(4-p-chlorophenylthio)-3′,5′-monophosphorothioate (Sp-8-pCPT-cGMPS; 10 μM) blocked this effect (63±1 mmHg; P<0.05 vs dobutamine alone, n=5).
6. At the end of reperfusion, LVDevP was 58±5 mmHg, i.e. 55% of pre-ischaemic value in control hearts, significantly increased to ∼80% by high concentrations of nitroprusside (100 or 1000 μM) or L-NOARG at 1 μM, while a high concentration of L-NOARG (1000 μM) reduced LVDevP to ∼35% (P<0.05 vs control; n=6).
7. Ischaemia increased tissue cyclic GMP levels 1.8 fold in control hearts (P<0.05; n=12); nitroprusside at 1 μM had no sustained effect, but increased cyclic GMP ∼6 fold at 1000 μM; L-NOARG (1 or 1000 μM) was without effect (n=6). Nitroprusside (1 or 1000 μM) marginally increased cyclic AMP levels whereas NO synthase inhibitors had no effect (n=6).
8. In conclusion, the cardioprotective effect of NO donors, but not of low concentrations of NO synthase inhibitors may be due to their ability to elevate cyclic GMP levels. Because myocardial cyclic GMP levels were not affected by low concentrations of NO synthase inhibitors, their beneficial effect on ischaemic and reperfusion function is probably not accompanied by reduced formation of NO and peroxynitrite in this model.

     

诱导型一氧化氮合酶在哮喘大鼠肺组织及中性粒细胞中的表达及地塞米松对其的影响

目的：观察诱导型一氧化氮合酶（iNOS）在哮喘大鼠肺组织及血中性粒细胞（PMN）中的表达,探讨PMN参与哮喘炎症的可能作用机制。方法：采用大鼠哮喘模型,随机分成哮喘组、对照组、地塞米松干预组,分离纯化血PMN,免疫组织化学法检测iNOS蛋白的表达水平,测定支气管肺泡灌洗液（BALF）中NO浓度。结果：哮喘组PMNiNOS蛋白光密度（OD）值（0.122±0.017）的表达水平显著高于对照组OD值（0.076±0.014）（P〈0.01）,地塞米松干预组OD值（0.089±0.013）PMNiNOS蛋白的表达水平显著低于哮喘组OD值（P〈0.01）,但与对照组相比差异无统计学意义。哮喘组支气管壁iNOS蛋白OD值（0.243±0.039）的表达水平显著高于对照组（0.119±0.016）（P〈0.01）,地塞米松干预组OD值（0.164±0.016）支气管壁iNOS蛋白的表达水平显著低于哮喘组且高于对照组（P均〈0.01）。哮喘组BALFNO浓度（8.59±1.07）ng/mL显著高于对照组（3.69±1.00）ng/mL（P〈0.01）,地塞米松干预组BALFNO浓度（4.28±0.89）ng/mL显著低于哮喘组（P〈0.01）,但与对照组相比差异无统计学意义。PMNiNOS蛋白的表达水平与BALFNO浓度呈显著正相关（n=29,r=0.770,P〈0.01）。支气管壁iNOS蛋白的表达水平与BALFNO浓度呈显著正相关（n=29,r=0.802,P〈0.01）。结论：哮喘大鼠PMN合成iNOS蛋白的功能增加,PMN可能通过iNOS参与哮喘的发病机制,这种功能可以部分被地塞米松所抑制。