牛磺酸对果糖诱导的高血压胰岛素抵抗大鼠红细胞L-精氨酸/一氧化氮途径的影响

目的和方法:在4%果糖引起大鼠胰岛素抵抗高血压模型上,观察红细胞L-精氨酸(L-Arg)/一氧化氮(NO)途径的改变,并观察牛磺酸对其改变的影响。结果:饮用果糖大鼠血压、血糖、血浆胰岛素水平明显高于对照大鼠的同时,红细胞对L-Arg总的转运及Y⁺载体转运的最大转运速率(V_max)分别低于对照大鼠31%和37％(P＜0.01);米氏常数(Km)分别比对照大鼠高35%和30%(P＜0.01)。红细胞内一氧化氮合酶(NOS)活性、cGMP水平和血浆NO含量明显低于对照大鼠(P＜0.01)。应用牛磺酸治疗可明显逆转上述改变(P＜0.01)。结论:胰岛素抵抗高血压大鼠存在有红细胞L-Arg/NO系统的功能障碍,牛磺酸可显著提高红细胞对L-Arg的转运速率和NOS活性。     

左旋精氨酸对被动吸烟孕鼠及胎仔发育的作用及其与NO、NOS的关系

目的了解左旋精氨酸对被动吸烟所致大鼠宫内发育迟缓及胎仔生长发育的作用,通过其与NO、NOS的关系探讨其作用机理.方法利用被动吸烟法建立大鼠IUGR模型,孕鼠随机分为5组:对照组、模型组、低剂量左旋精氨酸组、中剂量左旋精氨酸组、高剂量左旋精氨酸组.孕21天剖宫取胎,观察胎盘重、仔重、仔脑重、仔肝重;检测孕鼠血清及胎盘组织中NO含量及iNOS、cNOS活性.结果与对照组比较,模型组孕鼠胎盘重及仔重、仔脑重、仔肝重均明显降低(P<0.01),孕鼠血清及胎盘组织NO含量下降,iNOS活性升高,cNOS活性下降(P<0.01).低剂量及中剂量左旋精氨酸组与模型组比较各指标均有改善,但高剂量左旋精氨酸组与模型组比较无明显差异.结论孕中期应用一定剂量左旋精氨酸可有效防治被动吸烟孕鼠IUGR的发生并对胎仔发育有显著促进与保护作用,其作用与NO/NOS系统有关系.     

败血症休克大鼠血管外膜L-精氨酸/一氧化氮合酶/一氧化氮通路的变化

目的：观察败血症休克大鼠主动脉外膜L-精氨酸（L-Arg）转运，一氧化氮合酶（NOS）活性和一氧化氮(NO)生成的变化。方法:雄性Wistar大鼠盲肠结扎并穿孔复制败血症休克模型。测定大鼠主动脉外膜亚硝酸盐(NOx)含量、一氧化氮合酶(NOS)活性及L-精氨酸(L-Arg)转运；RT-PCR方法测定诱导型一氧化氮合酶(iNOS) mRNA水平。结果:严重感染休克大鼠呈现严重的血流动力学紊乱, 心功能抑制。败血症休克大鼠表现为严重的低血糖和高乳酸血症。血管外膜iNOS的mRNA水平均明显高于假手术组（均P<0.01），主动脉外膜NOx生成、NOS活性及L-Arg转运速率显著高于假手术组（P<0.01）。结论:败血症休克时血管外膜L-Arg/NOS/NO系统激活在败血症休克发病中可能起重要作用。     

维生素D3引起大鼠血管钙超载对血管L-精氨酸/NO途径的影响

目的：观察血管钙超载对Ｌ－精氨酸／ＮＯ途径的影响。方法：维生素Ｄ３（ＶｉｔＤ３）注射引起大鼠血管钙超载,检测血管ＮＯ生成、ｃＧＭＰ含量、Ｌ－瓜氨酸转化及Ｌ－精氨酸转运的变化,并与口服Ｌ－精氨酸治疗组大鼠比较。结果：大鼠血管钙含量（９４４±１８８）ｖｓ对照（１０７±１８）μｍｏｌ／ｇ干重,（Ｐ＜００１）,血管ＮＯ生成减少,组织ｃＧＭＰ含量降低,但Ｌ－瓜氨酸转化增高,Ｌ－精氨酸（Ｌ－Ａｒｇ）高和低亲和性转运的最大速率（Ｖｍａｘ）分别降低５０５％和４５８％（Ｐ＜００１）。口服Ｌ－Ａｒｇ治疗的大鼠血管ＮＯ生成和ｃＧＭＰ含量都较钙超载大鼠明显增高（Ｐ＜００１）,Ｌ－Ａｒｇ高、低亲和性转运的Ｖｍａｘ增加。结论：血管钙超载对Ｌ－Ａｒｇ／ＮＯ途径损伤的主要环节在Ｌ－Ａｒｇ的跨膜转运,补充ＮＯ前体Ｌ－Ａｒｇ可能减轻钙超载引起的血管损伤。     

原发性高血压患者红细胞L-精氨酸/一氧化氮系统的改变

目的:探讨原发性高血压时人体红细胞L-精氨酸/一氧化氮系统的变化。方法:原发性高血压患者(EH)12例与健康成年人10例作对照,制备红细胞悬液,分别测定红细胞的一氧化氮(NO)产生量、红细胞一氧化氮合酶(NOS)活性、红细胞cGMP含量和L-精氨酸(L-Arg)转运的动力学特征。结果:原发性高血压患者红细胞NO产生量明显低于对照组(P<0.01),红细胞cGMP含量也少于对照组27.2%(P<0.05)。EH患者红细胞NOS活性仅为对照组的47.8%(P<0.01)。其L-精氨酸转运总能力与Y⁺载体转运系统的转运能力明显低于正常人(P<0.01),而Y⁺L载体转运系统的转运能力无明显改变(P>0.05)。L-精氨酸总转运的最大速率与Y⁺载体转运系的最大速率分别较对照组降低36.8%和42.5%(P<0.01),各组间米氏常数无差异。结论:原发性高血压患者红细\胞L-Arg/NOS/NO/cGMP系统存在明显异常。     

一氧化氮及一氧化氮合酶在急性吸入高浓度氧大鼠肺泡上皮细胞凋亡中的作用

目的: 观察一氧化氮及其合酶在急性吸入高浓度氧大鼠肺泡上皮细胞凋亡中的作用。方法: 60只大鼠随机分为空气对照组(21%O₂)和高氧实验组4 h组、8 h 组、12 h组和16 h组(85%~100%O₂),每组12只,雌雄各半。比色法测定血浆、肺组织匀浆中丙二醛(MDA)、一氧化氮(NO)和一氧化氮合酶(NOS)活性。Western blotting检测肺组织中eNOS和iNOS蛋白表达。采用TUNEL染色法检测肺泡表面凋亡细胞,HE染色观察肺组织病理改变。结果: 与对照组比较,高氧各时相组血浆及肺组织匀浆MDA、NO、NOS均升高,差异显著(P<0.01)。对照组eNOS明显表达,高氧4 h组表达开始升高,8 h组eNOS蛋白质表达升高明显。对照组iNOS蛋白微量表达,但表达量远低于eNOS,16 h组表达略增强。与对照组(2.17%±1.80%)比较,4 h组肺泡上皮细胞凋亡数量增加9.13%±3.20%,8 h组、12 h组及16 h组凋亡细胞的数量增加达17.47%±3.50%、19.22%±4.50%和11.03%±2.80%。高氧各组血浆及肺组织各指标与细胞凋亡呈明显的正相关。结论: NO及eNOS在急性高氧诱导的肺泡上皮细胞凋亡的过程中可能发挥介导作用。     

感染性休克下调大鼠血管内皮和血小板L-精氨酸/一氧化氮通路

目的：观察感染性休克对大鼠血小板及血管L-精氨酸(L-Arg)/一氧化氮合酶(NOS) /一氧化氮(NO)通路的影响及其相互联系,探讨感染性休克损伤的机制。方法:利用盲肠结扎并穿孔复制早期和晚期感染性休克大鼠模型,采用Greiss法测定血管各层及血小板孵育液亚硝酸盐(NO^-₂/NO^-₃)含量;以同位素示踪法检测其NOS活性及L -Arg转运。结果:早、晚期感染性休克大鼠血小板和主动脉内膜NO-2/NO-3水平、NOS 活性及低亲合L-Arg 转运量均显著低于假手术组(高亲合L- Arg 转运量在早期休克增加、晚期休克降低);而中膜和外膜的NO^-₂/NO^-₃水平、NOS 活性及L-Arg 转运量则显著高于假手术组,均以休克晚期改变为显著。血小板和主动脉内膜NO^-₂/NO^-₃生成、NOS 活性及高、低亲合L-Arg 转运的改变均呈正相关(均P< 0. 01)。结论:感染性休克下调血管内膜和血小板的L-Arg/NO通路,上调血管中膜和外膜L-Arg/ NO通路。提示检测血小板L-Arg/NO通路的变化可能反映休克时血管内皮功能的损伤。     

Colitis generates remote antinociception in rats: the role of the l-arginine/NO/cGMP/PKG/KATP pathway and involvement of cannabinoid and opioid systems

Objective and design

The aim of this study was to investigate the possible involvement of the NO/cGMP/PKG/K _ATP ⁺ pathway, cannabinoids and opioids in remote antinociception associated with 2,4,6-trinitrobenzene sulph onic acid (TNBS)-induced colitis.

Methods

TNBS-induced colitis was induced by intracolonic administration of 20 mg of TNBS in 50 % ethanol. After induction, carrageenan (500 μg/paw) or prostaglandin (PG) E₂ (100 ng/paw) was injected in the rat’s plantar surface and hypersensitivity was evaluated by the electronic von Frey test. Rats were pre-treated with l-Noarg one hour before carrageenan injection. l-Arginine was given 10 min before l-Noarg injections. ODQ, KT 5823, glibenclamide (Glib), naloxone and AM 251 or AM 630 were administered 30 min prior to carrageenan or PGE₂ treatments.

Results

Colitis induction by TNBS reduced PGE₂ or carrageenan-induced hypersensitivity. Antinociception produced by TNBS-induced colitis was reversed significantly (P < 0.05) by l-Noarg, ODQ, KT 5823, glibenclamide, naloxone, AM251 and AM630 treatments.

Conclusions

TNBS-induced colitis causes antinociception in the rat paw. This disorder appears to be mediated by activation of the NO/cGMP/PKG/K_ATP pathway, endocannabinoids and endogenous opioids. This information may contribute to a better understanding of peripheral neurological dysfunctions occurring in Crohn’s disease.     

Effect of uncoupling NO/cGMP pathways on carbachol- and CCK-stimulated Ca2+ entry and amylase secretion from the rat pancreas

 Nitric oxide (NO) production reportedly regulates guanosine 3′,5′-cyclic monophosphate (cGMP) formation and Ca²⁺ influx in pancreatic acini. We have investigated the functional roles of the NO/cGMP messenger system in rat pancreatic acini. In dispersed acini, the levels of amylase secretion, cytosolic [Ca²⁺]([Ca²⁺]_i), NO synthase, and cGMP were measured. The NO synthase inhibitor N ^G-nitro-L-arginine methyl ester (L-NAME, 0.01–100 μM) had no effect on amylase secretion induced by various concentrations of carbachol, cholecystokinin octapeptide (CCK-8) or the high affinity CCK agonist, JMV-180. Similarly, L-NAME up to 100 μM did not affect the changes in Ca²⁺ spiking evoked by these secretagogues; nor was Ca²⁺ entry, refilling or oscillation altered by L-NAME. Sub- and supramaximal concentrations of these secretagogues did not change NO synthase activities compared with basal levels. While sodium nitroprusside (SNP), a NO donor, caused a 9.4-fold increase in cGMP levels compared with basal levels, carbachol, CCK-8 and JMV-180 had no effect. In addition, the guanylate cyclase inhibitor LY 83583 (10 nM to 10 μM) altered neither amylase secretion nor Ca²⁺ signaling induced by these secretagogues. These findings indicate that the stimulatory action of carbachol or CCK-8 is not mediated by NO or cGMP. To investigate whether cGMP stimulates pancreatic secretion we showed that both SNP and a cell-permeant cGMP analog at 0.1–1 mM stimulated amylase secretion and Ca²⁺ transients to a level equal to 10–15% and 13–24%, respectively, of those observed with maximal concentrations of secretagogues. The guanylate cyclase activator guanylin (1–10 μM), which increased cGMP levels 2.4-fold compared with basal levels, elicited a small amount of amylase secretion and a small Ca²⁺ transient. In conclusion, exogenous NO is capable of increasing endogenous cGMP, which results in a modest increase in the [Ca²⁺]_i transient and pancreatic amylase secretion. However, the NO/cGMP system does not appear to be involved significantly in the mediation of Ca²⁺ signaling and amylase secretion stimulated by carbachol and CCK-8. Received: 30 October 1996 / Received after revision and accepted: 13 January 1997     

实验性精索静脉曲张大鼠睾丸组织和血清一氧化氮和一氧化氮合酶的改变

目的：检测实验性精索静脉曲张大鼠睾丸组织和血清NO含量和NOS活性的改变，以进一步阐明精索静脉曲张的发生机制。方法：通过手术方法建立大鼠精索静脉曲张模型，检测NO和NOS的变化。结果：实验组左侧睾丸组织NO含量显著高于对照组左侧睾丸含量；实验组血清NOS活力明显低于对照组。结论：实验性精索静脉曲张大鼠睾丸组织和血清NO和NOS有改变。     

一氧化氮降低失血性休克血管反应性的机制

目的:探讨NO在失血性休克血管低反应性发生中的作用机制和防治。方法:复制SD大鼠失血性休克模型,测定脊斜肌微动脉对去甲肾上腺素(NE)的反应性。休克至血管反应性下降时,用同位素标记底物法测定脏器中NOS活性;分离肠系膜细动脉血管平滑肌细胞(ASMC),用荧光探针和共聚焦显微镜测定NO底物左旋精氨酸(L-Arg)和诱导性NOS(iNOS)抑制剂氨基胍(AG)对膜电位的影响;回输全部失血同时给L-Arg和AG观察其对大鼠24h存活率的影响。结果:休克至血管反应性降低时,心、肝NOS活性增加。L-Arg对对照组大鼠ASMC的膜电位无影响,但可使反应性低下大鼠的ASMC超极化;用AG预处理ASMC,则降低L-Arg引起的超极化幅度。回输全部失血时给AG可增加大鼠24h存活率。结论:HS后期ASMC中iNOS激活导致NO产生增加,并引起ASMC超极化可能是失血性休克后期血管低反应性发生的机制之一。     

乙烯雌酚诱导的大鼠垂体瘤模型的建立

目的:观察己烯雌酚诱导大鼠垂体瘤成瘤的稳定性,为后继研究提供实验基础。方法:60只标准Wistar-Furth大鼠随机分成己烯雌酚注射组、灭菌花生油注射组和对照组,每组20只,观察处理后大鼠一般情况、体重及行为学改变,并分别于4周、8周、和12周处死大鼠,观察成瘤情况和垂体重量变化,HE染色及免疫组化染色的方法鉴别肿瘤类型及CD31表达。结果:处理后2周,己烯雌酚注射组大鼠体重增长明显较其余2组缓慢,并出现脱毛、行动缓慢等表现。在相应时点处死大鼠,实验组出现肿瘤形成,4周、8周和12周成瘤率分别为30%、90%和100%,其余2组成瘤率为0。HE染色可见异常细胞。免疫组化鉴别均为催乳素(PRL)腺瘤,部分混杂促肾上腺皮质激素(ACTH)。实验组垂体组织无论成瘤与否,CD31阳性表达率与对照组相比差异显著。成瘤与否跟大鼠性别无关。结论:腹腔注射己烯雌酚诱导Wistar-Furth大鼠垂体瘤模型成瘤效果确切稳定。在成瘤过程中,部分指标出现动态变化,可以作为进一步研究的模型。     

The role of ATP sensitive K+ channels and of nitric oxide synthase on myocardial ischemia/reperfusion-induced apoptosis

During ischemia, ATP-sensitive K+ channels (KATP channels) open, and this triggers necrotic processes and apoptosis. In this study, we investigated whether selective sarcoplasmic and mitochondrial KATP channel blockers affected myocardial apoptosis and nitric oxide synthase (NOS) activity in a rat model of myocardial ischemia/reperfusion in vitro. Isolated rat hearts were subjected to 30 min of coronary artery occlusion followed by 30 min of reperfusion. A selective sarcKATP channel blocker, HMR1098 and a selective mitoKATP channel blocker, 5-hydroxydecanoate, were added to the perfusion fluid 10 min before occlusion. Myocardial apoptosis was detected immunohistochemically using the TUNEL method. Myocardial inducible NOS (iNOS) and endothelial NOS (eNOS) were determined immunohistochemically. In control hearts, apoptosis induction was associated with a greater immunoreactivity of iNOS than eNOS. Treatment with HMR1098, at a concentration of 3 micromol/l, significantly reduced the TUNEL-positive cardiomyocytes and this was associated with decreased iNOS and increased eNOS immunoreactivity. When this drug was administered at a higher concentration, at 30 micromol/l, a more marked reduction in apoptosis was observed but, in contrast to the effects observed at the lower drug concentration, eNOS immunoreactivity was almost completely abolished while iNOS was strong. Moreover, ischemia-induced cardiac dysfunction (e.g. contractile force and recovery of coronary flow) was increased by the higher concentration of HMR 1098. In hearts treated with 5-hydroxydecanoate, myocyte apoptosis was slightly reduced, and this was associated with an almost equal increase in both iNOS and eNOS immunoreactivity. These findings suggest that iNOS appears to be more important than eNOS in the reduction of apoptosis. However, the further inhibition of apoptosis by the higher concentration of HMR 1098 was associated with poorer cardiac function.     

Peripheral estradiol induces temporomandibular joint antinociception in rats by activating the nitric oxide/cyclic guanosine monophosphate signaling pathway

Recently, we have reported that high physiological estradiol level during the proestrus phase of the estrous cycle or systemic estradiol administration in ovariectomized rats decreases formalin-induced temporomandibular joint nociception. However, the mechanisms underlying the antinociceptive effect of estradiol are presently unknown. In this study, we used the temporomandibular joint formalin model in rats to investigate whether estradiol decreases nociception by a peripheral non-genomic mechanism, and if so, whether this mechanism is mediated by the activation of the nitric oxide–cyclic guanosine monophosphate signaling pathway and of opioid receptors. The administration of estradiol into the ipsilateral, but not into the contralateral temporomandibular joint significantly reduced formalin-induced temporomandibular joint nociception in ovariectomized and diestrus but not in proestrus females. However, the administration of the estrogen receptor antagonist ICI 182780 into the ipsilateral, but not into the contralateral temporomandibular joint blocked the antinociceptive effect of serum estradiol in proestrus females, suggesting that the physiological effect of estradiol in nociception is mediated, at least in part, by a peripheral mechanism. The administration of estradiol into the ipisilateral temporomandibular joint did not affect formalin-induced nociception in male rats. The antinociceptive effect of temporomandibular joint estradiol administration in ovariectomized and diestrus females was mimicked by estradiol conjugated with bovine serum albumin, which does not diffuse through the plasma membrane, and was blocked by the estrogen receptor antagonist ICI 182780. The administration of the nitric oxide synthase inhibitor (nitro-l-arginine) or of a guanylate cyclase inhibitor (1H-(1,2,4)-oxadiasolo (4,2-a) quinoxalin-1-one) into the ipsilateral, but not into the contralateral temporomandibular joint blocked the antinociceptive effect of estradiol and of estradiol conjugated with bovine serum albumin, while the opioid receptor antagonist naloxone had no effect. These findings suggest that estradiol decreases temporomandibular joint nociception in female rats through a peripheral non-genomic activation of the nitric oxide–cyclic guanosine monophosphate signaling pathway.     

内皮素和一氧化氮/一氧化氮酶检测对老年糖尿病与血管病变患者临床价值的研究

探讨内皮素(ET)、一氧化氮/一氧化氮酶( NO/NOS)在糖尿病与血管病变患者中的变化。ET采用放射免疫分析法,NO/NOS采用酶法。结果是:(1)糖尿病组ET水平(68.80±37.35)pg/mL)较对照组(41.70±21.50pg/mL)显著升高(P<0.001);NOS水平(2.75±1.49U/mL)明显高于对照组(1.12±0.56U/mL),P<0.01;NO水平(49.32± 16.32μmol/L)明显低于对照组(54.60 ±15.60μmol/L),P<0.05。(2)糖尿病合并血管病变组ET水(80.1140.25pg/mL)显著高于无并发症组(62.73±24.29pg/mL),P<0.001;NOS水平(4.02 ± 0.59U/mL)明显高于无并发症组(2.51±1.19U/mL),P<0.001;NO水平(42.25 ± 10.10/μmol/L)明显低于无并发症组(52.16±14.59mol/L,P<0.05;NO/NOS(11.99±7.05)明显低于无并发症组(26.9±13.15),P<0.001提示 ET、NO/NOS与糖尿病的发生和发展有关,联合检测不仅可作为糖尿病及其血管并发症的重要依据,还将有助于糖尿病合并血管病变的预防和治疗。     

Effects of intrarectal and intraperitoneal N(G)-nitro-L-arginine methyl ester treatment in 2,4,6-Trinitrobenzenesulfonic acid induced colitis in rats

Inflammatory bowel disease (IBD) has been associated with an increased generation of nitric oxide (NO). Different authors have shown that NO in IBD can be either harmful or protective. The aim of this study was to investigate the efficiency of intrarectal (i.r.) and intraperitoneal (i.p.) application of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-specific nitric oxide synthase inhibitor, in experimental acute colitis in the rats. Acute colitis was induced in rats by 2,4,6-trinitrobenzenesulfonic acid (TNBS) and ethanol. Twenty-eight rats were divided into four groups. L-NAME (50 mg/kg/day) was administered i.p. (Group 1) and i.r. (Group 2) for 7 days following the day when colitis was induced. Group 3 rats were not given any treatment after induction of colitis. Control group rats were given saline solution i.r. instead of TNBS. The presence of hyperemia, inflammation and ulcer was evaluated to score of macroscopic morphologic damage. The severity of colitis was assessed by microscopic criteria including ulceration, mucus cell depletion, crypt abscesses, inflammatory cysts, mucosal atrophy, edema, inflammatory cell infiltration, and vascular dilatation. Rectal tissue myeloperoxidase (MPO) activity and serum-rectal tissue nitrite levels were measured. Serum and rectal tissue nitrite levels increased in Group 3 rats. Both i.p. and i.r. L-NAME treatment significantly reduced serum and rectal tissue nitrite levels, but no effect on MPO activity and histologic damage score was observed. Under the present conditions we concluded i.r. and i.p. L-NAME treatment, applied at the dosage of 50 mg/kg/day, does not have any protective effect on the colonic injury.     

急性缺氧大鼠血浆、呼出气NO含量的变化及吸入NO对缺氧性肺血管收缩的影响

观察了大鼠急性缺氧前后血浆和呼出气一氧化氮（ＮＯ）含量的变化，结果显示，动物吸人１０％，２０ｍｉｎ后，血浆ＮＯ＿２／ＮＯ＿３浓度从２３．５６±７．１３升至４１．６３±１０．１０μｍｏｌ／Ｌ（Ｐ＜０．０１）；呼出气ＮＯ浓度出０．０９９±０．０５５增至０．１６２±０．１０８ｐｐｍ（Ｐ＜０．０１）．提示急性缺氧时ＮＯ生成增多可能在缺氮性肺血管收缩（ＨＰＶ）中起调节作用。为探讨吸入ＮＯ对ＨＰＶ的影响，本文采用人工呼吸给缺氧大鼠吸入４０ｐｐｍＮＯ，发现动物缺氧（１０％Ｏ＿２）１０ｍｉｎ后，平均肺动脉压（ｍＰＡＰ）和肺血管阻力（ＰＶＲ）较基础值明显升高（Ｐ＜０．０１）：而缺氧同时吸入４０ｐｐｍＮＯ１０ｍｉｎ，ｍＰＡＰ和ＰＶＲ较缺氧时明显降低（Ｐ＜０．０１），与基础值无显著差别（Ｐ＞０．０５），且发现△ＰＶＲ％为２．９４±９．８５％，较缺氧时６６．１８±２３．３９％明显降低（Ｐ＜０．０１），但吸入ＮＯ对体动脉压、体血管阻力，心输出量、血气和高铁血红蛋白无明显影响。从而提示吸入ＮＯ选择性降低缺氧性肺动脉高压且完全逆转ＨＰＶ。     

Relative significance of the nitric oxide (NO)/cGMP pathway and K+ channel activation in endothelium‐dependent vasodilation in the femoral artery of developing piglets

Mechanisms mediating endothelium‐dependent vasodilation were investigated in femoral artery rings from <2‐day‐old (newborn) and 2‐week‐old piglets. Based on previous results we hypothesized an age difference in the relative contribution of nitric oxide(NO)‐cyclic 3′,5′‐guanosine monophosphate (cGMP) and K⁺ channel‐activation to acetylcholine (ACh)‐induced vasodilation. Changes in vascular tone were studied in organ baths in the absence or presence of NO synthase(NOS) inhibition or K⁺ channel blockade and the intra‐arterial accumulation of cGMP in response to ACh was measured with radioimmunoassay (RIA). In control experiments, relaxant responses to ACh were equal in the two age groups. In the presence of the NOS‐inhibitors N ^G‐monomethyl‐L ‐arginine acetate (L ‐NMMA; 100 μM ) or N^G‐nitro‐L ‐arginine (L ‐NOARG; 1–100 μM ), however, relaxation was significantly more reduced in femoral artery rings from 2‐week‐old than from newborn, with lower pD₂ values in the older age group. Inhibition of large (BK_Ca) conductance calcium‐sensitive K⁺ channels with tetraethylammonium chloride (TEA; 1 mM ), gave a significant rightward shift in the concentration‐response curves to ACh which was of the same magnitude in both age groups. The ACh‐induced vasodilation was abolished in both age groups by high K⁺ (20 mM ) in combination with L ‐NOARG (100 μM ). The relative increase in cGMP levels after addition of ACh (10 nM ) was significantly larger in rings from newborn compared with 2‐week‐old piglets (12‐ vs. four‐fold). In summary, sensitivity to NOS inhibition increased with age while the effect of K⁺ channel blockade with TEA was the same in femoral artery rings from newborn to 2‐week‐old piglets. Lower sensitivity to NOS inhibition and a larger increase in cGMP in response to ACh could indicate a higher efficacy of the NO/cGMP pathway in this vessel in the newborn piglet.     

Involvement of nitrergic and opioidergic systems in the hypothermia induced by cholestasis in rats

Background and aim: Cholestatic animals display abnormal hypothalamic responses to pyrogenic stimuli and decreased febrile response to lipopolysaccharide. The present study was undertaken to determine if obstructive cholestasis was associated with abnormal thermoregulation under thermoneutral conditions. Methods: Male Sprague–Dawley rats weighing 200–250 g were randomly divided into 21 groups. Three sets of seven groups were unoperated control, sham-operated and bile duct-ligated rats. The groups of unoperated control, sham-operated and bile duct-ligated rats were treated with daily administration of isotonic saline solution, N(ω)-nitro-l-arginine methyl ester (l-NAME) (3, 10, or 20 mg/kg), naltrexone (10 or 20 mg/kg) or aminoguanidine (150 mg/kg). Body temperatures were measured before and 1, 3, 5 and 7 days after the surgery. Results: Bile duct-ligated rats had lower body temperature than sham-operated animals at 3 (P < 0.001) and 5 (P < 0.01) days after surgery. l-NAME, a non-selective inhibitor of nitric oxide synthase (NOS) (10, 20 mg/kg, i.p.) or aminoguanidine, a selective iNOS inhibitor (150 mg/kg, i.p.), completely reversed this hypothermia (P > 0.05). Naltrexone, a non-selective opioid antagonist (20 mg/kg, i.p.), also completely corrected this hypothermia (P > 0.05). There was a drop in temperature in the first day after the surgery in sham and BDL groups compared to unoperated controls, which was significant in some groups demonstrating the effect of surgery and anesthetic drugs on the body temperature. Conclusions: Cholestatic rats show impaired thermoregulation suggesting the involvement of nitrergic and opioidergic systems.     

慢性低氧过程中肺血管内皮细胞损伤和一氧化氮合酶变化

目的：观察慢性低氧时肺血管内皮细胞及肺内一氧化氮合酶（NOS）的改变。方法：利用常压低氧舱复制大鼠慢性低氧模型，使用电镜技术观察肺血管内皮细胞的改变，采用还原型辅酶Ⅱ硫辛酸脱氢酶（ND）细胞化学染色及NOS免疫组化染色观察NOS的改变。结果：肺血管内皮细胞损伤、脱落，肺动脉肌化，随着低氧时间延长，血管内皮细胞NOS蛋白表达递增，但一氧化氮（NO）作用反而减弱。结论：慢性低氧可引起肺血管内皮细胞的损伤、肺内NOS含量和活性增加及内皮源性舒张因子（EDRF）的作用减弱，以致肺动脉发生肌化。