蜂胶总黄酮的舒血管效应及其机制探讨

目的:探讨蜂胶总黄酮(total flavonoids of propoli,TFP)对大鼠的胸主动脉舒张作用及其可能作用机制。方法:SD雄性大鼠随机分为4组(n=6):即对照组(CG),TFP低、中、高剂量(50、100、200mg/kg)组(即LG、MG和HG组),各组大鼠按TFP低、中、高剂量等容积灌胃(1次/d),CG大鼠等容积生理盐水灌胃(1次/d),连续4周。主动脉取血3~5mL测量血小板聚集率,制备离体胸主动脉环,经生物信号采集分析系统记录主动脉环张力变化,观察各组大鼠血管环对去氧肾上腺注射液(PE)和KCl刺激的收缩反应,同时检测各组大鼠胸主动脉环匀浆一氧化氮(NO)含量及诱导型一氧化氮合酶(iNOS)活性。结果:与CG组相比,TFP呈剂量依赖性抑制大鼠血小板聚集率;对内皮完整的主动脉环,在KCl(12~60mmol/L)预收缩的基础上,TFP呈剂量依赖性舒张作用;在PE(1×10-6 mol/L)预收缩的基础上,TFP也呈剂量依赖性改善乙酰胆碱(ACh)(1×10-8~1×10-5 mol/L)的舒张效应;非选择性一氧化氮合酶(NOS)抑制剂N-硝基-L-精氨酸甲酯(L-NAME)(10-4 mol/L)或环氧合酶抑制剂吲哚美辛(Indo,10-5 mol/L)预孵育后,TFP对PE(10-8~10-5 mol/L)诱导下的各组血管环的收缩反应均增强。生化检查结果显示,与CG组相比,TFP呈剂量依赖性提高胸主动脉环iNOS活性和NO含量。结论:TFP呈剂量依赖性抑制大鼠血小板聚集率;TFP剂量依赖性改善大鼠血管的舒张功能,提示其舒张效应是通过改善血管内皮细胞功能及阻滞电压门控Ca2+通道有关,改善血管内皮细胞功能可能是使其增加释放NO和前列环素(PGI2)实现的,至于其阻滞Ca2+通道机制有待进一步探讨。     

多沙唑嗪光学异构体对小鼠膀胱逼尿肌作用及作用机制研究

目的观察多沙唑嗪[(±)Dox]及其对映体[(-)Dox和(+)Dox]对小鼠离体膀胱逼尿肌的作用并分析其机制。方法采用小鼠离体膀胱条张力实验及电场刺激诱发小鼠离体膀胱条收缩实验。结果卡巴胆碱浓度依赖性诱发小鼠膀胱逼尿肌收缩,苯肾上腺素对小鼠膀胱逼尿肌无收缩作用。1μmol/L的(-)Dox、(+)Dox或(±)Dox对卡巴胆碱诱发的收缩反应均无显著影响(P>0.05),1μmol/L的Atr可完全阻断其收缩反应;(-)Dox、(+)Dox和(±)Dox对电场刺激诱发小鼠膀胱逼尿肌收缩反应无显著影响(P>0.05)。结论药物或电刺激诱发的小鼠膀胱逼尿肌收缩反应无去甲肾上腺素能成分的参与,多沙唑嗪及其对映体对其收缩反应无影响。     

儿茶酚抑素对大鼠离体血管环张力的影响

目的研究儿茶酚抑素(CST)对大鼠离体血管环的效应及其可能的机制。方法记录苯肾上腺素(PE)预收缩的大鼠离体胸主动脉环张力变化,观察不同浓度CST的作用效果以及应用L-硝基-精氨酸甲酯(L-NAME)抑制一氧化氮(NO)生成后的作用效果的变化。结果①PE(10-9～10-5mmol/L)对大鼠离体血管环有浓度依赖性的收缩作用;②CST在10-8～10-4mol/L浓度范围内对PE(10-6mmol/L)引起的血管收缩有浓度依赖性的舒张作用,其舒张作用较同等浓度的乙酰胆碱(Ach)和硝普钠(SNP)均弱;③用L-NAME(10-4mol/L)预处理后,CST的作用明显减弱。结论 CST对PE诱发的血管收缩有浓度依赖性的舒张作用,血管内皮释放的NO可能是CST的作用途径之一。     

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。     

补骨脂素和补骨脂酚舒张血管的作用机制研究

目的:探讨补骨脂素和补骨脂酚舒张血管的作用机制。方法:取大鼠胸主动脉制备离体血管环及去内皮血管环。采用血管收缩率为考察指标,分别以一氧化氮合酶抑制剂N-硝基-L-精氨酸甲酯(L-NAME,100μmol/L)预孵育内皮完整或去内皮血管环后,考察低、中、高剂量补骨脂素或补骨脂酚(0.1、1、10μmol/L)对去甲肾上腺素(NE,1μmol/L)或氯化钾(KCl,60 mmol/L)预收缩血管环的舒张作用;分别以钙依赖型钾离子通道抑制剂氯化四乙胺(TEA,0.1 mmol/L)、内向整流型钾离子通道抑制剂氯化钡(BaCl2,0.1 mmol/L)预孵育去内皮血管环后,考察低、中、高剂量补骨脂酚(0.1、1、10μmol/L)对NE(1μmol/L)预收缩去内皮血管环的舒张作用。采用胶原酶-中性蛋白酶混合消化法分离大鼠心脏微血管内皮细胞,采用酶联免疫吸附法考察低、中、高剂量补骨脂素或补骨脂酚(0.1、1、10μmol/L)对细胞中内皮型一氧化氮合酶(eNOS)蛋白表达的影响。结果:各剂量补骨脂素和补骨脂酚均能显著降低NE预收缩的内皮完整血管环收缩率(P<0.01),中、高剂量补骨脂素和补骨脂酚能显著降低KCl预收缩的内皮完整血管环收缩率(P<0.05或P<0.01),而去内皮和抑制一氧化氮合酶后血管环收缩率显著升高(P<0.05或P<0.01);中、高剂量补骨脂酚能显著降低NE预收缩去内皮血管环收缩率(P<0.05或P<0.01),而抑制血管平滑肌内向整流型钾离子通道后血管环收缩率显著升高(P<0.01)。各剂量补骨脂素和补骨脂酚均能显著提高大鼠心脏微血管内皮细胞中e NOS蛋白表达水平(P<0.01)。结论:补骨脂素和补骨脂酚可能通过内皮依赖性的NO途径以及促进内皮细胞中eNOS蛋白表达来发挥血管舒张作用;补骨脂酚还可能通过开放内向整流型钾离子通道这一非内皮依赖途径发挥血管舒张作用。     

钾通道抑制剂减弱吉非罗齐对离体大鼠胸主动脉环的舒张作用

目的观察吉非罗齐对大鼠离体胸主动脉肌源性反应的影响,并探讨其作用机制。方法采用离体血管张力方法观察吉非罗齐对SD大鼠胸主动脉环静息张力及苯肾上腺素(PE)预收缩的影响;观察一氧化氮合成酶(NOS)抑制剂、环氧合酶抑制剂和K+通道阻断剂对吉非罗齐作用的影响。结果吉非罗齐(1×10-5～3×10-4mol.L-1)对大鼠胸主动脉静息张力无影响,但对PE(10-6mol.L-1)所致的预收缩具有浓度依赖性舒张作用,其最大舒张率为最大舒张的80.42%±6.35%。电压依赖性钾通道(KV)阻断剂四氨基吡啶(4-AP,10-3mol.L-1)、钙激活钾通道(KCa)阻断剂四乙胺(TEA,10-2mol.L-1)、内向整流钾通道(KIR)阻断剂氯化钡(BaCl2,10-3mol.L-1)和ATP敏感钾通道(KATP)阻断剂格列苯脲(Gli,10-5mol.L-1)均可减弱吉非罗齐的血管舒张作用(P<0.05),而一氧化氮合酶(NOS)抑制剂L-NAME(10-4mol.L-1)及环氧酶抑制剂吲哚美辛(10-5mol.L-1)对吉非罗齐的舒张作用无影响(P>0.05)。结论吉非罗齐对大鼠主动脉具有舒张作用,该舒张作用与NO及前列环素无关;可能与开放KV、KCa、KIR和KATP通道有关。     

不同浓度依托咪酯对内毒素孵育前后兔离体肺、体动脉环张力的影响

目的研究不同浓度依托咪酯(Etomidate,Eto)对内毒素(Lipopolysaccharide,LPS)孵育前后的离体兔肺动脉和主动脉环张力的影响,为临床脓毒性休克麻醉药选择提供依据。方法制备兔离体肺动脉环和主动脉环,随机分为4组:正常肺动脉环组、LPS孵育后肺动脉环组、正常主动脉环组、LPS孵育后主动脉环组,观察Eto在去氧肾上腺素预收缩动脉环的作用下,Eto剂量分别为1.0、2.0、10.0μmol/L时,对4组肺动脉和主动脉环的张力作用。结果 Eto的给药量为1.0μmol/L时,LPS孵育前后肺、主动脉环张力无明显变化(P>0.05);2.0μmol/L时,正常肺、主动脉环和LPS孵育后主动脉环张力明显上升(P<0.05);10.0μmol/L时,LPS孵育的肺、主动脉环的张力较正常肺、主动脉环明显下降(P<0.05)。结论低浓度Eto收缩机制占主导,但随着浓度增加,Eto引起内毒素孵育后肺动脉舒张的程度比体动脉更明显,可能与高浓度Eto抑制血管收缩功能有关。     

咪达唑仑舒张大鼠离体胸主动脉环的机制研究

目的观察咪达唑仑对大鼠离体胸主动脉环张力的影响,并探讨其作用机制。方法采用离体血管张力试验方法,观察咪达唑仑在3×10-6,1×10-5,3×10-5,1×10-4mol/L浓度时,对去甲肾上腺素(NE,1×10-6mol/L)诱发大鼠离体胸主动脉环收缩的影响。观察内皮细胞型一氧化氮合酶(eNOS)抑制剂左旋硝基精氨酸甲酯(L-NAME,1×10-4mol/L)、一氧化氮供体L-精氨酸(L-Arg,1×10-5mol/L)、特异性钙非依赖可诱导型(iNOS)抑制剂N-3-氨甲基-苄基-乙酰氨(1400W,1×10-5mol/L)对咪达唑仑作用的影响,以及咪达唑仑对血管环外钙依赖性收缩和内钙依赖性收缩的影响。结果以上浓度的咪达唑仑对NE预收缩的大鼠离体胸主动脉环有舒张作用。用L-NAME、L-NAME合用L-Arg预处理的血管环对咪达唑仑的舒张反应与未经处理时比较,差异有统计学意义(P<0.05),L-Arg和1400W对咪达唑仑的舒血管作用没有影响(P>0.05)。1×10-4mol/L的咪达唑仑可明显抑制血管环外钙依赖性收缩和内钙依赖性收缩(P<0.05)。结论咪达唑仑对大鼠胸主动脉环具有浓度依赖性的舒张作用,其舒张反应可能与内皮产生的一氧化氮有关,通过抑制外钙内流和内钙释放发挥舒张作用。     

汉黄芩素增强乙酰胆碱对大鼠胸主动脉血管的舒张作用研究

目的探讨汉黄芩素增强乙酰胆碱对大鼠胸主动脉血管的舒张作用及其作用机制。方法实验分为对照组和加药组,加药组使用含有不同浓度汉黄芩素的DMEM/F12培养基作用;对照组使用含有与加药组相同体积二甲基亚砜(DMSO)的DMEM/F12培养基作用。汉黄芩素孵育大鼠心脏微血管内皮细胞24 h,MTT法检测细胞活力;硝酸还原酶法检测细胞上清NO含量;ELISA法检测细胞内皮型一氧化氮合酶(eNOS)蛋白表达。汉黄芩素孵育大鼠胸主动脉环24h,去甲肾上腺素(1×10~(-6) mol/L)收缩血管后应用乙酰胆碱(1×10~(-8)、1×10~(-7)、1×10~(-6)、1×10~(-5)mol/L)舒张血管,检测血管张力变化。结果与对照组比较,汉黄芩素处理细胞后,各组细胞活力没有显著变化。与对照组比较,汉黄芩素(5、20μmol/L)显著促进NO的产生(P0.01),但亚硝基左旋精氨酸甲酯(L-NAME)可以抑制汉黄芩素的这种作用(P0.01)。汉黄芩素(0.5、5、20μmol/L)可以浓度相关性地促进心脏微血管内皮细胞eNOS蛋白表达,与对照组比较,汉黄芩素产生的eNOS蛋白水平差异非常显著(P0.01)。乙酰胆碱(1×10~(-8)、1×10~(-7)、1×10~(-6)、1×10~(-5)mol/L)能够浓度相关性地舒张离体大鼠胸主动脉环。与对照组比较,汉黄芩素(20μmol/L)孵育血管24h,能显著增加乙酰胆碱对大鼠胸主动脉血管环的舒张程度,降低胸主动脉血管环的收缩率(P0.01、0.05)。结论汉黄芩素可能通过促进血管内皮细胞eNOS蛋白表达和NO产生这一途径增强乙酰胆碱对血管的舒张作用。     

2型糖尿病大鼠不同时期膀胱收缩力动态变化的实验研究

目的观察2型糖尿病(T2DM)大鼠不同时期膀胱收缩力的动态变化情况,以探讨糖尿病膀胱病变的病理生理学机制。方法制备T2DM大鼠模型,以同龄正常大鼠为对照,在成模后6、12和20周,应用M受体激动剂卡巴胆碱,在不同药物浓度水平下进行离体逼尿肌环收缩刺激实验。结果 6周时实验组的最大收缩力(1.12±0.16)g/mg,比对照组(0.99±0.06)g/mg增高;半数有效剂量浓度(EC50)实验组(1.7±0.4)×10-7mol/L比对照组(2.7±0.3)×10-7mol/L降低;12周时实验组的最大收缩力(1.20±0.12)g/mg与对照组(1.21±0.08)g/mg差异无统计学意义;EC50实验组(2.2±0.4)×10-7mol/L与对照组(2.3±0.4)×10-7mol/L差异无统计学意义;20周时实验组的最大收缩力(1.01±0.05)g/mg比对照组(1.90±0.09)g/mg降低;EC50实验组(2.7±0.4)×10-7mol/L比对照组(2.0±0.4)×10-7mol/L增高。结论不同时期的糖尿病大鼠膀胱收缩力表现不同,随着病程的进展,膀胱逼尿肌收缩力呈现先增高后降低的趋势,对卡巴胆碱的敏感性也呈现先增高后降低的变化趋势。     

（—）Epicatechin induces and modulates endotheliumdependent relaxation in isolated rat mesenteric artery rings

AIM:The present study was aimed to examine the role of endothelial nitric oxide in the relaxant response to green tea (-)epicatechin and its modulation of endothelium-mediated relaxation in the isolated rat mesenteric artery rings.METHODS:Changes in the isometric tension were measured with Grass force-displacement transducers.RESULTS:The (-)epicatechin-induced relaxation was largely dependent on the presence of intact endothelium and was reversed by N^G-nitro-L-arginine methyl ester 10μmol/L or methylene blue 10μmol/L,the inhibitors of nitric oxidemediated relaxation.L-Arginine at 1mmol/L antagonized the effect of L-NAME or methylene blue.Pretreatment of endothelium-intact rings with (-)epicatechin 10μmol/L enhanced the relaxation induced by endothelium-dependent vasodilator,acetylcholine,while this concentration did not influence the endothelium-independent relaxation induced by sodium nitroprusside in the endothelium-denuded artery rings.CONCLUSION:The results indicate that the endothelium-dependent vasodilation by (-)epicatechin is mainly mediated through nitric oxide and low concentration of (-)epicatechin augments endothelium-dependent vasorelaxation in the rat mesenteric arteries.     

依那普利对大鼠离体胸主动脉的舒张作用及其机制

目的：观察依那普利对血管的直接作用，并探讨其机制。方法：采用Powerlab生物信号采集系统记录依那普利对去甲肾上腺素（NE）和KCl预收缩的离体大鼠胸主动脉环舒张作用，观察左旋硝基精氨酸甲酯（L—NAME，10^-4mol／L）和吲哚关辛（10^-8mol／L）对其作用的影响。结果：在内皮完整的大鼠离体胸主动脉环，依那普利（10^-9～10^-4mol／L）对NE（10^-5mol／L）或KCl（20mmol／L）引起的收缩具有浓度依赖性的舒张作用。去内皮后，依那普利的舒血管作用显著减弱。在内皮完整的血管环，L—NAME（10^-4mol／L）和吲哚美辛（10^-8mol／L）对依那普利的舒血管作用具有明显的抑制作用。结论：依那普利对大鼠离体胸主动脉环具有浓度依赖性的舒张作用，此作用具有内皮依赖性，与内皮产生的NO和前列环素（PGI2）有关。     

高浓度曲马朵通过内皮依赖与非依赖机制诱导家兔主动脉舒张(英文)

AIM: The mechanism of tramadol-induced vasodilation was investigated using isolated rabbit thoracic aortic rings. METHODS: Aortic rings from 8 rabbits were placed in organ bath and precontracted with phenylephrine(10~(-5) mol/L) before addition of tramadol. Relaxation responses by tramadol were evaluated in the presence and absence of endothelium, indomethacin (an inhibitor of cyclooxygenase), N~G-nitro-L-arginine methyl ester (L-NAME, a specific inhibitor of nitric oxide synthase), glibenclamide (an inhibitor of ATP-sensitive potassium channels), tetraethylammonium chloride (TEA, an inhibitor of calcium-sensitive potassium channels), and naloxone (an antagonist of opioid receptors). RESULTS: Tramadol(10~(-4) mol/L and 3×10~(-4) mol/L) caused significant vasodilation in endothelium-intact and endothelium-denuded aortic rings (P<0.05). The relaxation response to tramadol was significantly greater in endothelium-intact rings than in endothelium-denuded rings. Pretreatment of aortic rings with indomethaci     

Effect of pravastatin on impaired endothelium-dependent relaxation induced by lysophosphatidylcholine in rat aorta

Aim: To investigate the effects of pravastatin, a potent 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on impaired endothelium-dependent relaxation induced by lysophosphatidylcholine (LPC), the major component of oxidized low-density lipoprotein, in rat thoracic aorta. Methods: Both the endothelium-dependent relaxation response to acetylcholine and the endotheliumindependent relaxation response to sodium nitroprusside of aortic rings were measured by recording isometric tension after the rings were exposed to LPC in the absence or presence of pravastatin to estimate the injury effect of LPC and the protective effect of pravastatin on the aortic endothelium, respectively. Results: Exposure of aortic rings to LPC (1-10μmol/L) for 30 min induced a significant concentration-dependent inhibition of endothelium-dependent relaxation to acetylcholine, but did not affect endothelium-independent relaxation in response to sodium nitroprusside. Pre-incubation of aortic rings with pravastatin (0.3-3mmol/L) for 15 min and then co-incubation of the rings with LPC (3 μmol/L) for another 30 min significantly attenuated the inhibition of endothelium-dependent relaxation induced by LPC. This protective effect of pravastatin (1 mmol/L) was abolished by N^G-nitro-L-arginine methyl ester (30 μmol/L), an inhibitor of nitric oxide synthase, but not by indomethacin (10 μmol/L), an inhibitor of cyclooxygenase. Moreover, protein kinase C inhibitor chelerythrine (1μmol/L) the superoxide anion scavenger superoxide dismutase (200 kU/L), and the nitric oxide precursor L-arginine (3 mmol/L) also improved the impaired endotheliumdependent relaxation induced by LPC, similar to the effects of pravastatin.C onclusion: Pravastatin can protect the endothelium against functional injury induced by LPC in rat aorta, a fact which is related to increasing nitric oxide bioavailability.     

COMPARISON OF RESPONSES TO AMINOGUANIDINE AND Nω-NITRO-L-ARGININE METHYL ESTER IN THE RAT AORTA

1. We have compared the effect of aminoguanidine with that of N^ω-nitro-L-arginine methyl ester on isolated thoracic aortic rings obtained either from endotoxin (lipopolysaccharide, 10 mg/kg, i.v. for 3 h) or vehicle (saline) treated rats. 2. Administration of endotoxin for 3h resulted in a hypo tension and a significant reduction of pressor responses to nor-epinephrine (1 μg/kg, i.v.) in the anaesthetized rat. 3. In intact rings obtained from vehicle treated rats, amino guanidine (0.3 and 1mmol/L) had no significant effect on acetylcholine-induced relaxation (10^-9–10^-5mol/L), whereas N^ω-nitro-L-arginine methyl ester (0.3mmol/L and 1mmol/L) abolished that response, suggesting that aminoguanidine does not inhibit the activity of constitutive nitric oxide synthase. 4. Relaxation induced by L-arginine (10^-6–10^-2mol/L) was competitively inhibited by both aminoguanidine (0.3 mmol/L) and N^ω-nitro-L-arginine methyl ester (0.3 mmol/L) in endo thelium-denuded aortic rings obtained from endotoxin treated rats. 5. Three hours of endotoxaemia was associated with an impairment of contraction to norepinephrine (10^-9–10^-6 mol/L) in the endothelium-denuded aorta ex vivo. This hyporeactivity to norepinephrine was partially restored by treatment of the vessels either with aminoguanidine (0.3 mmol/L) or with N^ω-nitro-l-arginine methyl ester (0.3 mmol/L) in vitro. 6. These results in isolated thoracic aortae of the rat reinforce that aminoguanidine is a selective inhibitor of the inducible nitric oxide synthase, whereas N^ω-nitro-L-arginine methyl ester is a non-selective inhibitor of both the inducible and constitutive nitric oxide synthase.     

Baicalin-induced vascular response in rat mesenteric artery: role of endothelial nitric oxide

1. Baicalin was isolated and purified from the dry roots of Scutellaria baicalensis Georgi (Huangqin; a traditionally used Chinese medicinal herb) and its effect on the contractility of rat isolated mesenteric arteries was investigated and the role of the endothelium was examined. 2. The concentration-dependent contractile response to U46619 was enhanced by 10(-5) mol/L baicalin in endothelium-intact rings, but this effect was abolished in the presence of 10(-4) mol/L N(G)-nitro-L-arginine or in endothelium-denuded rings. 3. Pretreatment of endothelium-intact rings with baicalin (3 x 10(-5) mol/L) markedly attenuated the relaxant response to A23187, thapsigargin and acetylcholine. 4. The present results indicate an important role for endothelial nitric oxide (NO) in the vascular response to baicalin. Baicalin appears to inhibit NO production and release in the endothelium and this mechanism is likely to be responsible for the enhancement of the U46619-induced contraction and for inhibition of endothelial NO-mediated relaxation by baicalin in rat mesenteric artery.     

内吗啡肽抑制苯肾上腺素和血管紧张素Ⅱ诱导的离体大鼠胸主动脉环收缩

目的:研究吗啡、内吗啡肽-1和内吗啡肽-2对由苯肾上腺素(PE)和血管紧张素(Ang)Ⅱ诱导离体大鼠胸主动脉环收缩的抑制作用.方法:离体血管环张力试验.结果:与对照组相比,吗啡、内吗啡肽-1和内吗啡肽-2的预处理(0.1-10μmol/L)能明显降低由PE(0.1μmol/L)和Aug Ⅱ(1μmol/L)(P<0.01)诱导离体大鼠胸主动脉环的张力,但是不能减少去内皮血管的张力.纳络酮(1μmol/L)能部分阻断内吗啡肽-1和内吗啡肽-2的抑制作用(P<0.01),N~(ω)-nitro-L-arginine(10μmol/L)或血管环去内皮能完全阻断这种作用(P<0.01).结论:内吗啡肽-1和内吗啡肽-2通过纳络酮敏感方式抑制由PE和AngⅡ诱导的离体大鼠胸主动脉环收缩,这种抑制作用可能与血管内皮NO的释放有关.     

Effects of a new class of no-releasing NSAIDs on platelets and isolated arteries

A new class of nitroderivatives of non-steroidal anti-inflammatory drugs has recently been synthesized (Nicox Ltd., London, UK). In order to improve gastric tolerance of the parent compound, a side-chain, able to release nitric oxide, has been added to the core structure of the molecule. We studied in vitro the effects of nitrofenac and two NO-aspirins (NCX 4215 and NCX 4016) on platelets and isolated arteries to identify any possible effect due to the release of nitric oxide or to the inhibition of cyclo-oxygenase activity. Nitrofenac induced a dose-dependent relaxation both with intact (46% with 1×10⁻³ mol/L) and endothelium-denuded (75% with 1×10⁻³ mol/L) rings of rat aorta precontracted with epinephrine, while diclofenac did not affect this contraction (0% relaxation in intact and 22% in rubbed arteries). Pretreatment with diclofenac 1×10⁻³ mol/L significantly increased the vasorelaxant effects of nitrofenac at each drug concentration, both in intact (86% with 1×10⁻³ mol/L) and rubbed preparations (89%). NO-aspirins, unlike acetylsalicylic acid, were able to relax both intact and endothelium-denuded rings of rat aorta (100% relaxation). Methylene blue and oxyhaemoglobin completely reversed the relaxation induced by nitrofenac and NO-aspirins, both in rubbed and intact aortic rings. Both NO-aspirins exhibited antiaggregating properties in archididonic acid-stimulated human platelets, measured using a turbidimetric method (NCX 4215, 1×10⁻³ mol/L: 70% inhibition; NCX 4016 1×10⁻⁴ mol/L: 100%), NCX 4016 proving as effective as acetylsalicylic acid 1×10⁻⁵ mol/L. Thrombin-induced platelet aggregation was inhibited in acetylsalicylic acid-treated platelets (NCX 4215, 1×10⁻³ mol/L: 50%, NCX 4016, 1×10⁻⁴ mol/L: 92%). NCX 4016 was also able to provent thrombin-induced intracellular free calcium increase, effect not observed with acetylsalicylic acid. In vitro thromboxane A₂ production in human platelets, assayed RIA as thromboxane B₂ serum concentration, was reduced by NCX 4215, 1×10⁻³ mol/L (76%) and virtually abolished by NCX 4016 5×10⁻⁵ mol/L (95% inhibition). These results demonstrate in vitro the antiaggregating activity of NO-aspirins, NCX 4016 being more active than NCX 4215, and the vasorelaxant effects of all the tested molecules. The mechanism involved in two-fold: release of nitric oxide and inhibition of cyclo-oxygenase.     

根皮素的心血管保护作用研究

目的 研究根皮素对狗冠状动脉舒张特征的影响及其机制.方法 制备狗冠状动脉血管环,固定于盛有K-H液的恒温肌槽内,并观察等长时血管张力的变化.结果 10 μmol·L-1或30 μmol· L-1 L根皮素使KCl及无钙K-H液中CaCl2量效曲线明显右移,使血管环敏感性和最大收缩反应明显降低.30 μmol· L-1根皮素在50 mmol· L-1 KCl预收缩的离体冠脉血管环产生一个明显的急性舒张,加入Nω-L-硝基精氨酸1×10-4mol·L-1、普蔡洛尔1×10-5 mol· L-1、亚甲蓝1×10-5 mol·L-1、二硝酸异山梨醇酯(吲哚美辛)1×10-5 mol·L-1及去内皮细胞后,根皮素的急性舒张血管作用不受影响.结论 根皮素在离体冠脉血管环的舒张效应主要是通过抑制电压依赖性钙通道实现的.根皮素的这种舒张效应与NO、内皮、β肾上腺素受体和前列腺素类皆无关.     

17β-OESTRADIOL ENHANCES NITRIC OXIDE SYNTHASE ACTIVITY IN ENDOTHELIUM-DENUDED RAT AORTA

1. It has been suggested that oestrogen-produced vasodilatation is due to induction of endothelial nitric oxide synthase (NOS), but there are many reports of direct effects on vascular smooth muscle. In the present study, these processes were investigated in rat aorta isolated from ovariectomized rats. 2. Short-term treatment (10min) with 17β-oestradiol (10 μmol/L) produced a small attenuation of the phenylephrine (PE)-induced constriction, which was unaffected by the nitric oxide synthase inhibitor l-N 5(-1-iminoethyl)ornithine (NIO; 100μmol/L). Long-term treatment (6h) with 17β-oestradiol (10 μmol/L) did not affect acetylcholine-mediated vasorelaxation in endothelium-intact aortic rings, but did attenuate PE-induced constriction. This attenuation was also observed in endotheliumdenuded preparations after 17β-oestradiol (10 μmol/L for 6h) and was far greater than the acute effect of 17β-oestradiol (10 μmol/L). 3. The attenuation produced by 17β-oestradiol (10 μmol/L for 6 h) was significantly inhibited by concomitant treatment with cycloheximide (1 μmol/L), suggesting that protein synthesis was involved. NIO (100 μmol/L) also attenuated the effect, which suggests that the anti-constrictor effect of 17β-oestradiol occurs through the increased production of nitric oxide (NO). 17β-Oestradiol increased NO production, as assessed by the conversion of [³H]-arginine to [³H]-citrulline in rat aorta. These effects were prevented by cycloheximide and NIO. The anti-constrictor effect of oestrogen was blocked by the oestrogen receptor antagonist ICI 182780 (100nmol/L). 4. Western blotting using an antibody specific for inducible nitric oxide synthase (NOS) revealed that 17β-oestradiol (10 μmol/L for 24 h) treatment induced the formation of inducible NOS protein in the aorta, an effect blocked by cycloheximide. The results indicate that 17β-oestradiol can attenuate the vasoconstrictor effect of PE by a specific receptor-mediated process that involves induction of inducible NOS.