染料木素对狗基底动脉环舒张作用及其机制的离体研究

目的：探讨血管张力变化对染料木素的脑血管保护作用及相关机制的比较。方法：（1）制备狗基底动脉血管环固定于恒温肌槽内,待平衡后,加入各种药物观察血管张力的变化。结果：（1）200μmol／L GST可浓度依赖性地压低氯化钾（KCl）量效曲线,使其明显右移,最大收缩反应和肌条对KCl的敏感性明显降低。（2）无Ca^2＋K—H液中。染料术素对去甲肾上腺素（NA）诱发产生第一时相收缩和CaCl2产生第二时相收缩均具有明显的抑制作用。（3）染料木素可使60mmol／L KCl预收缩基底动脉血管环产生明显的舒张作用,除内皮细胞或加入一氧化氮合酶抑制剂Nω—L-硝基精氨酸1×10^-4mol／L．甲烯兰1×10^-5mol／L．1×10^-5mol／L吲哚美辛或格列本脲1×10^-5mol／L温育后,染料木素对60mmol／L KCl预收缩动脉血管环产生的量效舒张作用无明显改变（P〉0．05）。结论：（1）染料木素对基底动脉血管舒张可能是直接作用于平滑肌而引起的,即抑制电压依赖性的钙通道。无Ca^2＋K—H液中,抑制NA从细胞内释放贮存的Ca^2＋。（2）染料木素对基底动脉血管的舒张作用与内皮细胞及其释放的一氧化氮无关。前列腺素类物质的合成和KATP通道亦无关。     

鸟苷对大鼠胸主动脉血管环的舒张作用及机制

目的研究鸟苷对大鼠离体血管环的影响,并探讨其可能的作用机制。方法分离SD大鼠胸主血管环,分成去内皮组和内皮完整组,采用离体血管环实验方法,经生物信号采集与分析系统测定血管环张力的变化,观察鸟苷的舒血管作用并探讨不同抑制剂对鸟苷舒张大鼠离体血管环作用的影响。结果鸟苷(10-9～10-5 mol.L-1)对基础状态下或KCl预收缩血管环的张力无影响;对PE预收缩的血管环有内皮依赖性舒张作用;环氧合酶抑制剂吲哚美辛孵育对鸟苷的舒张作用无明显影响;一氧化氮合酶抑制剂L-NAME或鸟苷酸环化酶抑制剂亚甲蓝可阻断鸟苷的血管舒张作用。结论鸟苷对大鼠离体胸主动脉有浓度依赖性舒张作用,其舒张作用可能与NO-GC-cGMP途径相关。     

原花青素对狗离体冠状血管的影响在药理学范畴的研究

目的:研究原花青素在狗冠状动脉上舒张特征和机制。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:原花青素使KCl及无钙中CaCl2量效曲线明显右移,使肌条敏感性和最大收缩反应明显降低。原花青素可使KCl预收缩冠状动脉血管环产生明显的舒张作用,Nω-L-硝基精氨酸、甲烯兰及去内皮细胞组,可部分阻断17β-雌二醇的舒张作用。结论:原花青素具有内皮依赖性和非内皮依赖性的舒血管效应,前者的作用机制与NO和NO-cGMP途径相关,而后者可能是由于原花青素对血管的直接作用引起,即抑制电压依赖性的钙通道。     

白藜芦醇对离体犬冠状动脉血管环的影响

目的：研究白藜芦醇和17β-雌二醇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：白藜芦醇和17β-雌二醇使KCI及无钙K-H液中CaCl2量效曲线明显右移，使肌条敏感性和最大收缩反应明显降低。Nω-L-硝基精氨酸、甲烯兰、正矾酸钠及去细胞内皮，可部分阻断白藜芦醇和17β-雌二醇的舒张血管作用。格列本脲组对白藜芦醇和17β-雌二醇的舒张作用没有影响。结论：白藜芦醇和17β-雌二醇舒张血管都具有内皮依赖性，与KATP仰通道无关。     

荞麦花叶总黄酮的舒张血管作用及其机制

目的探讨荞麦花叶总黄酮(TFBFL)对大鼠离体胸主动脉的舒张作用与机制。方法采用离体血管环灌流装置,经生物信号采集与分析系统测定血管环张力的变化;激光扫描共聚焦显微镜技术检测血管平滑肌细胞内钙浓度。结果在苯肾上腺素(phenylephrine,PE)10-6mmol.L-1或KCl60 mmol.L-1预收缩的保留内皮和去除内皮的血管环中,TFBFL均能够浓度依赖性的引起血管舒张;相对于去除内皮的血管环,TFBFL对保留内皮的血管环的舒张作用更明显。保留内皮的血管环用一氧化氮合酶抑制剂L-NAME(100mmol.L-1)预孵后,TFBFL诱导的血管舒张作用明显减弱。在无钙灌流液中,用KCl 60 mmol.L-1去极化去除内皮的血管环后,逐渐加入Ca2+,使血管环呈浓度依赖性收缩;TFBFL(0.8 mg.L-1)孵育10 min后可使CaCl2的量效曲线向下移位且可使PE在无钙灌流液中诱导的血管环最大收缩幅度明显降低。激光扫描共聚焦显微镜检测细胞内钙的结果表明,TFBFL浓度依赖性(0.4、0.8 mg.L-1)的抑制了静息状态平滑肌细胞质内钙浓度的升高。结论 TFBFL能够浓度依赖性舒张大鼠胸主动脉,其作用机制可能是降低细胞内游离Ca2+浓度;对于保留内皮的血管环,TFBFL也作用于血管内皮细胞,促进一氧化氮的释放,引起血管舒张。     

乙酰异羟肟酸的舒张血管作用及其机制

目的研究乙酰异羟肟酸(AHA)降血压和舒张胸主动脉血管的作用及其机制。方法 (1)动物实验:8周龄SD雄性大鼠,ip给予AHA 50和100 mg·kg-1,每5 d给药1次,共5次。分别在给药前1 d、给药第13天和给药第26天测收缩压(SBP)和舒张压(DBP);HE染色观察大鼠胸主动脉血管组织形态变化。(2)离体实验:①累积浓度AHA(0.1,1,3,10,30和100μmol·L^-1)处理大鼠离体胸主动脉内皮完整血管环,检测血管环张力。②大鼠离体胸主动脉内皮完整和去内皮血管环用去甲肾上腺素(NE,1μmol·L^-1)和KCl(60 mmol·L^-1)预收缩,稳定后每10 min累积加入AHA(0.1,1,3,10,30和100μmol·L^-1),计算血管舒张百分比。③内皮完整血管环分为AHA组、AHA+左旋硝基精氨酸甲酯(L-NAME)组和AHA+吲哚美辛(Indo)组。L-NAME(0.1 mmol·L^-1)或Indo(0.01 mmol·L^-1...     

同型半胱氨酸对血管内皮细胞功能损害的体外研究

目的：探讨高同型半胱氨酸血症对血管内皮细胞功能损伤的机制和改善其损伤的方法。方法：体外培养脐静脉血管内皮细胞，用RT-PCR方法检测血管内皮细胞在不同浓度的同型半胱氨酸或同时加入氟伐他汀孵育24h后血凝素样氧化低密度脂蛋白受体-1（LOX-1）和内皮型一氧化氮合酶（eNOS）的mRNA表达。结果：同型半胱氨酸实验组的LOX-1mRNA表达增多，其中100μmol／L组显著增多（P〈0．05）；各组之间eNOS的mRNA表达差异无统计学意义（P〉0．05）。同时加入氟伐他汀后，LOX-1和eNOS的mRNA表达均无显著改变（P〉0．05）。结论：高同型半胱氨酸血症可能通过提高血管内皮细胞的LOX-1水平加速动脉粥样硬化的进程，如何防治尚需进一步研究。     

阿托品对大鼠肠系膜动脉的舒张作用及机制

目的研究阿托品的扩血管作用及机制。方法以大鼠肠系膜动脉为标本，考察阿托品对去甲肾上腺素(NE)预收缩血管的舒张作用以及血管内皮细胞、血管平滑肌在该效应中的作用。结果阿托品能显著舒张NE预收缩的完整内皮血管，去内皮后该作用明显降低。L-N^ω-硝基精氨酸甲酯、吲哚美辛、普萘洛尔及格列本脲对阿托品的舒张作用无明显影响。阿托品对KCl的量效曲线及咖啡因缩血管作用均无明显影响，但能浓度依赖性地抑制NE诱导的内钙释放以及经受体操纵性钙通道的外钙内流。结论阿托品有明显的扩血管作用，其通过抑制受体介导的外钙内流和内钙释放而舒张血管。     

阿魏酸对离体大鼠冠状动脉的舒张作用及机制探讨

目的探讨阿魏酸(ferulic acid,FA)对离体大鼠冠状动脉的舒张作用及机制。方法采用微血管张力法,测定FA对静息及预收缩大鼠离体冠状动脉舒张作用;观察内皮对FA舒张作用的影响;探讨FA舒张作用与细胞外钙内流和内钙释放的关系;应用钙激活K~+通道(K_(Ca))阻断剂四乙胺(TEA)、ATP敏感K~+通道(K_(ATP))阻断剂格列苯脲(Gli)、内向整流K~+通道(KIR)阻断剂氯化钡(BaCl_2)、电压依赖性K~+通道(K_V)阻断剂4-氨基吡啶(4-AP)、NOS抑制剂L-硝基精氨酸甲酯(L-NAME)、环氧酶抑制剂吲哚美辛(Indo)等工具药,探究FA舒张大鼠离体冠状动脉的作用机制。结果 FA对大鼠离体冠状动脉静息张力无明显影响;浓度依赖性的舒张KCl(60 mmol·L~(-1))、U46619(1μmol·L~(-1))、PE(10μmol·L~(-1))预收缩的大鼠冠状动脉(P<0.05);内皮对FA舒张作用无明显影响(P>0.05);FA能够明显抑制外钙依赖性和内钙释放引起的血管收缩(P<0.05);4-AP(1mmol·L~(-1))能抑制FA的舒张作用,TEA、Gli、BaCl_2、LNAME、Indo无明显影响(P>0.05)。结论 FA对离体大鼠冠状动脉的舒张作用可能与血管平滑肌细胞上KV通道激活、细胞肌浆网内钙释放、外Ca~(2+)通道的阻滞有关,与K_(Ca)、K_(ATP)、K_(IR)通道无关,也不依赖于内皮功能。     

活血逐瘀方浸膏的舒张血管作用及其作用机制

目的观察活血逐瘀方浸膏的舒张血管作用，并探讨其作用机制。方法采用豚鼠肠系膜微血管和大鼠体外主动脉环研究活血逐瘀方浸膏舒张血管作用;硝酸还原酶法测定血浆一氧化氮(NO)和血管NO、一氧化氮合酶(NOS)、原生型一氧化氮合酶（cNOS）及诱生型一氧化氮合酶（iNOS）的活性。结果活血逐瘀方浸膏有抗去甲肾上腺素致豚鼠肠系膜微血管收缩的作用;松弛苯肾上腺素引起体外大鼠胸主动脉环收缩的作用，预加格列本脲或普萘洛尔后仍然有松弛作用，而去内皮后引起收缩作用;高剂量的活血逐瘀方浸膏非常显著性地升高血浆NO及主动脉NO含量、提高NOS和cNOS的活性;低剂量活血逐瘀方浸膏显著性提高血管cNOS的活性。结论活血逐瘀方浸膏有舒张血管的作用，其作用机制可能与其激活血管NOS、cNOS活性和促进血管内皮NO释放有关。     

EMD56431对犬冠脉和肠系膜动脉的作用

目的：研究ＥＭＤ对犬冠脉和肠系膜动脉的松弛作用。方法：用２０和６０ｍｍｏｌ／Ｌ ＫＣｌ激动冠脉（＋Ｅ,－Ｅ）,观察ＥＭＤ的松弛效应。同时观察格列本脲对ＥＭＤ松弛冠脉的影响及ＥＭＤ对ＫＣｌ量效曲线的改变。此外,还测定了ＥＭＤ松驰犬肠系膜动脉和冠脉的ＥＣ５０。结果：０．７μｍｏｌ／Ｌ ＥＭＤ对２０ｍｍｏｌ／Ｌ ＫＣｌ去极化冠脉无效;格列本脲能有效拮抗ＥＭＤ对冠脉的松驰作用;ＥＭＤ使５～３０ｍｍｏｌ／Ｌ     

EMD_(56431)对犬冠脉和肠系膜动脉的作用

研究表明：①0．7μmol／LEMD对20mmol／LKCl去极化冠脉（＋E,－E）呈非内皮依赖性松弛,而对60mmol／LKCI去极化冠脉则无效。②格列本脉能有效桔抗EMD对冠脉的松弛作用。③EMD可使低浓度KCl去极化思脉量效曲线呈非平行右移,拮抗作用明显,但对高浓度KCl刚失去拮抗作用,最大反应（Emax）不压低。④EMD松弛犬肠系膜动脉及冠脉的EC50（－LogC）分别为6．2和644。     

Responses of canine coronary arteries to transmural electrical stimulation and nicotine

In helical strips of dog coronary arteries contracted with prostaglandin F_2α, transmural electrical stimulation and nicotine elicited a transient relaxation. The response to electrical stimulation was abolished by tetrodotoxin, bretylium or pretreatment of the dogs with reserpine, and was potentiated by cocaine. Atropine was ineffective. The relaxations were abolished or converted to contractions by sotalol; the contraction was suppressed by phentolamine. The nicotine-induced relaxation was suppressed by hexamethonium, cocaine, bretylium and sotalol. Atropine and tetrodotoxin did not affect the response. Following pretreatment with reserpine, relaxant responses to nicotine were partly reduced; the remaining relaxations were suppressed by atropine, slightly inhibited by sotalol and potentiated by physostigmine. It may be concluded that electrical stimulation liberates norepinephrine from adrenergic nerves, which preferentially activates β-adrenoceptors. The reuptake mechanism appears to function to inactivate liberated norepinephrine. Nicotine-induced relaxations are mediated mainly by liberated norepinephrine; however, as shown by the pretreatment with reserpine, the release of an acetylcholine-like substance may also be involved.     

甲氨蝶呤对诱导型一氧化氮合酶的抑制活性及其机制研究

目的揭示甲氨蝶呤(MTX)对诱导型一氧化氮合酶(iNOS)的抑制活性及其机制,明确MTX、四氢生物蝶呤(BH4)和iNOS之间的相互作用。方法采用试剂盒方法测定MTX对iNOS的体外抑制活性,并采用计算机对接程序(DOCK)模拟MTX和iNOS的结合方式。结果浓度为112μmol/L的MTX对iNOS的抑制率为100%,其IC50为(44.64±4.47)μmol/L;MTX可完全占据BH4与iNOS的结合“腔穴”而与iNOS稳定结合。结论MTX是一种BH4的竞争性iNOS抑制剂,通过与iNOS活性位点的直接作用,进而抑制NO的产生。     

Balloon angioplasty and induction of non-endothelial nitric oxide synthase in rabbit carotid arteries

The purpose of the study was to evaluate whether balloon angioplasty is associated with changes in nitric oxide synthase (NO synthase) activity. Normal rabbit carotid arteries were examined 10 min or 1, 2, 3 or 10 weeks after angioplasty with 2 or 2.5-mm balloons. Immunohistology was used to evaluate intimal thickening and endothelial cell regeneration. The NO synthase activity was studied functionally using isolated segments in organ chambers. Immunohistochemistry of the endothelial cell markers von Willebrand factor and platelet endothelial cell adhesion molecule-1 indicated that the regeneration of endothelial cells from patchy islands that remained after angioplasty was virtually complete within 2 weeks. However, the endothelium-dependent relaxations elicited by acetylcholine remained impaired up to 10 weeks after dilatation. Contractions elicited by 5-hydroxytryptamine (5-HT) were attenuated, but were significantly augmented by the NO synthase blocker, nitro- -arginine. Furthermore, in contrast to normal arteries, the balloon-treated arteries developed marked contractions in response to nitro- -arginine methyl ester ( -NAME), contractions which could be reversed by -arginine. The latter contractions and relaxations were not influenced by endothelial removal. These results suggest that although the endothelium quickly regenerates after severe balloon injury, the endothelium-dependent release of nitric oxide remains disturbed. However, the functional data also suggest that angioplasty led to a significant induction of NO synthase in ‘non-endothelial’ cells of the artery.     

Evidence that mechanisms dependent and independent of nitric oxide mediate endothelium-dependent relaxation to bradykinin in human small resistance-like coronary arteries

1. The effects of the nitric oxide (NO) synthase inhibitor, N^G-nitro-L-arginine (L-NOARG), the NO scavenger, oxyhaemoglobin (HbO) and high extracellular K⁺ upon endothelium-dependent relaxation to bradykinin were investigated in human isolated small coronary arteries.
2. Endothelium-dependent relaxations to bradykinin were compared in vessels contracted to ∼50% of their maximum contraction to 124 mM KCl Krebs solution, regardless of treatments, with the thromboxane A₂ mimetic, U46619 and acetylcholine. All relaxations were expressed as percentage reversal of the initial level of active force.
3. L-NOARG (100 μM) caused a small but significant, 12% (P<0.01), decrease in the maximum relaxation (R_max: 91.5±5.4%) to bradykinin but did not significantly affect the sensitivity (pEC₅₀: 8.08±0.17). Increasing the concentration of L-NOARG to 300 μM had no further effect on the pEC₅₀ or R_max to bradykinin. HbO (20 μM) and a combination of HbO (20 μM) and L-NOARG (100 μM) reduced R_max to bradykinin by 58% (P<0.05) and 54% (P<0.05), respectively. HbO (20 μM) and L-NOARG (100 μM, combined but not HbO (20 μM) alone, caused a significant 11 fold (P<0.05) decrease in sensitivitiy to bradykinin. HbO (20 μM) decreased the sensitivity to the endothelium-independent NO donor, S-nitroso-N-acetylpenicillamine (SNAP), approximately 17 fold (P<0.05).
4. Raising the extracellular concentration of K⁺ isotonically to 30 mM, reduced the R_max to bradykinin from 96.6±3.1% to 43.9±10.1% (P<0.01) with no significant change in sensitivity. A combination of HbO, L-NOARG and high K⁺ (30 mM) abolished the response to bradykinin. High K⁺ did not change either the sensitivity or maximum relaxation to SNAP.
5. In conclusion, L-NOARG does not completely inhibit endothelial cell NO synthesis in human isolated small coronary arteries. By comparison, HbO appeared to block all the effects of NO in this tissue and revealed that most of the relaxation to bradykinin was due to NO. The non-NO -dependent relaxation to bradykinin in the human isolated small coronary arteries appeared to be mediated by a K⁺-sensitive vasodilator mechanism, possibly endothelium-derived hyperpolarizing factor (EDHF).

     

Effect of biochanin A on the aryl hydrocarbon receptor and cytochrome P450 1A1 in MCF-7 human breast carcinoma cells

Phytoestrogen biochanin A is an isoflavone derivative isolated from red clover Trifolium pratense with anticarcinogenic properties. This study examined the action of biochanin A with the carcinogen activation pathway that is mediated by the aryl hydrocarbon receptor (AhR) in MCF-7 breast carcinoma cells. Treating the cells with biochanin A alone caused the accumulation of CYP1A1 mRNA and an increase in CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity in a dose dependent manner. A concomitant treatment with 7,12-dimethylbenz[a]anthracene (DMBA) and biochanin A markedly reduced the DMBA-inducible EROD activity and CYP1A1 mRNA level. In addition, the biochanin A treatment alone activated the DNA-binding capacity of the AhR for the dioxin-response element (DRE) of CYP1A1, as measured by the electrophoretic-mobility shift assay (EMSA). EMSA revealed that biochanin A reduced the level of the DMBA-inducible AhR-DRE binding complex. Furthermore, biochanin A competed with the prototypical AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), for binding to the AhR in an isolated rat cytosol. The biochanin A competitively inhibited the metabolic activation of DMBA, as measured by the formation of the DMBA-DNA adducts. These results suggest that biochanin A may thus be a natural ligand to bind on AhR. Therefore, biochanin A may be due to act an antagonist/agonist of the AhR pathway.     

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。