Pharmacological interference of vascular smooth muscle cell hypertrophy induced by glycosylated human oxyhaemoglobin

Nonenzymatically glycosylated human oxyhaemoglobin induces vascular smooth muscle cell hypertrophy by releasing reactive oxygen species. We analysed the ability of drugs with antihypertrophic properties for the vascular wall and/or antioxidant activity, such as captopril, losartan, and nifedipine, or gliclazide, carvedilol, and ascorbic acid, to interfere with 10 nM glycosylated human oxyhaemoglobin-induced increase in vascular smooth muscle cell size (118+/-0.5% of basal). Vascular smooth muscle cell hypertrophy was abolished concentration-dependently, with pD(2) values over a 100-fold interval: 6.4+/-0.3, 7.7+/-0.4, 7.3+/-0.4, 7.4+/-0.6, 8. 8+/-0.2, and 9.0+/-0.2 for captopril, losartan, nifedipine, ascorbic acid, carvedilol and gliclazide, respectively. Drugs with powerful antioxidant properties, especially carvedilol and gliclazide, are particularly effective in preventing glycosylated human oxyhaemoglobin-induced vascular smooth muscle cell hypertrophy.     

维拉帕米诱导血管平滑肌细胞凋亡及其在再狭窄机制中的作用

目的探讨维拉帕米能否诱导血管平滑肌细胞凋亡及细胞凋亡在再狭窄机制中的作用。方法分别取正常兔髂动脉,动脉粥样硬化及再狭窄髂动脉血管中膜组织进行平滑肌细胞培养,［３Ｈ］ ＴｄＲ参入法测定细胞增殖活性,维拉帕米诱导平滑肌细胞凋亡,通过电镜观察,ＤＮＡ凝胶电泳及流式细胞仪了解各组平滑肌细胞凋亡情况。结果维拉帕米诱导下,平滑肌细胞的变化具有凋亡的典型特征。血管成形术后,细胞增殖及凋亡系统均被激活,再狭窄组细胞增殖程度增加２６％,细胞凋亡激活程度增加１９％,二者比例失衡。结论维拉帕米能够引起血管平滑肌细胞凋亡,而平滑肌细胞凋亡的相对减少在再狭窄的发生机制中发挥一定的作用。     

他汀类药物与血管平滑肌细胞凋亡

血管平滑肌细胞（VSMC）的异常增殖和迁移在粥样斑块形成和冠状动脉介入治疗（PCI）后再狭窄中起非常重要的作用。他汀类药物不仅是一种有效的调脂药，同时还有多种调脂以外的作用。如他汀类药物可以抑制VSMC的增殖和迁移，并诱导其凋亡。临近病变部位的中层VSMC的凋亡可能造成斑块纤维帽容易破裂，进而引起斑块不稳定和临床事件。但研究证实他汀类药物有稳定斑块的作用，且新生内膜VSMC对他汀类药物诱导的凋亡作用比普通的血管中层VSMC更敏感。因此，他汀类药物的促新生内膜VSMC凋亡作用可能对预防PCI术后再狭窄起有益作用。具体作用机制以及临床上如何合理发挥此类作用尚待进一步研究。     

牛磺酸拮抗溶血磷脂酸诱导的大鼠血管平滑肌细胞增殖作用

目的　观察牛磺酸 (Tau)对溶血磷脂酸 (LPA)诱导的大鼠血管平滑肌细胞 (VSMC)增殖作用的影响。方法　在培养的大鼠血管平滑肌细胞上 ,测定3 H 胸腺嘧啶核苷(3 H TdR)参入和丝裂素活化蛋白激酶 (MAPK)活性 ;硫代巴比妥酸盐 (TBA)法测脂质过氧化终产物丙二醛 (MDA)含量。结果　LPA (1× 10 -9～ 1× 10 -7mol·L-1)呈浓度依赖性增加VSMC 3 H TdR参入 ,5、10和 2 0mmol·L-1Tau及MAPK抑制剂PD0 980 59预孵育后分别使LPA (1× 10 -7mol·L-1)诱导的3 H TdR参入较单独LPA组减少 15 %、34%、4 8%和 5 4 % (P <0 0 5或P <0 0 1)。LPA增加VSMCMAPK活性 ,5、10和 2 0mmol·L-1Tau预孵育降低LPA(1× 10 -7mol·L-1)刺激的MAPK活性 ,较单纯LPA孵育低14 %、35 %和 4 4 % (P <0 0 5或P <0 0 1)。随着加入LPA的浓度增加 ,细胞MDA含量增加。与 1× 10 -7mol·L-1LPA组比较 ,5、10和 2 0mmol·L-1Tau预处理的细胞较LPA单独孵育组细胞MDA含量分别低 18%、2 7%、4 5 % (P<0 0 5或P <0 0 1) ,LPA诱导细胞MDA生成的作用不受PD0 980 59预孵育的影响 (P >0 0 5 )。结论　LPA呈浓度依赖性促进VSMC增殖和脂质过氧化 ,前者与其细胞内信号传导MAPK途径有关 ,Tau可有效拮抗LPA诱导的VSMC增殖、MAPK激活和脂质过氧化损伤 ,Tau     

普罗布考抑制过氧化氢诱导血管平滑肌细胞的凋亡

目的研究抗氧化剂普罗布考(probucol)对过氧化氢(H2O2)诱导血管平滑肌细胞(VSMCs)凋亡的影响。方法以1mmol·L-1H2O2为VSMC凋亡诱导剂,probucol浓度为100、10和1μmol·L-1,孵育6h,采用Annexin V-FITC染色、TUNEL法和Hoechst33258染色法观察细胞凋亡;Western blot检测细胞中ASK-1和Trx-1蛋白的表达。结果H2O2可促使VSMCs凋亡,细胞中ASK-1蛋白表达增加,Trx-1蛋白表达降低。Probucol可减轻H2O2所致的细胞凋亡,呈浓度依赖性;同时细胞中ASK-1蛋白表达降低,Trx-1蛋白表达增加。结论probucol能拮抗H2O2诱导的血管平滑肌细胞凋亡,其机制可能与降低细胞中ASK-1蛋白表达,升高Trx-1蛋白表达有关。     

Effects of captopril,losartan, and nifedipine on cell hypertrophy of cultured vascular smooth muscle from hypertensive Ren-2 transgenic rats

1. We hypothesized that tissular renin-angotensin system (RAS) induces vascular hypertrophy in hypertensive Ren-2 transgenic rats (TGR; strain name TGR(mRen2)L27). This assumption was tested in cell cultures of vascular smooth muscle (VSMC) from both hypertensive TGR and control normotensive Sprague-Dawley (SD) rats. Planar cell surface area, protein synthesis, and protein content per cell were studied, the role for locally produced angiotensin II (AII) was evaluated and the possible pharmacological interference by different drugs was analysed.
2. By use of radioimmunoassay techniques, AII could be determined in TGR cultures (10.25±0.12 pg per 10⁷ cells) while it could not be detected in SD ones.
3. Under serum-free conditions, VSMC from hypertensive TGR were hypertrophic when compared to SD VSMC, as they presented a higher protein content per cell (335±18 and 288±7 pg per cell respectively; P<0.05) and increased mean planar cell surface area, as determined by image analysis (4,074±238 and 4,764±204 μm², respectively; P<0.05).
4. When exogenously added to cultured SD and TGR VSMC, AII (100 pM to 1 μM) promoted protein synthesis and protein content in a concentration-dependent manner without affecting DNA synthesis. Maximal effects were observed at 100 nM. At this concentration, AII effectively increased planar cell surface area in both SD and TGR cultures by ∼20%.
5. Treatment of TGR cultures, in the absence of exogenous AII, with the angiotensin-converting enzyme inhibitor captopril or the angiotensin AT₁ receptors antagonist losartan (100 nM to 10 μM) reduced planar cell surface area in a concentration-dependent manner. In addition, both captopril and losartan (10 μM), decreased protein synthesis by ∼15%.
6. Treatment of SD VSMC, in the absence of exogenous AII, with both captopril and losartan had no effect either on planar cell surface area or protein synthesis.
7. Treatment with the Ca²⁺ antagonist nifedipine (100 nM to 10 μM) reduced cell size in both SD and TGR cultures. Maximal cell reduction reached by nifedipine averaged 906±58 and 1,292±57 μm², in SD and TGR, respectively (P<0.05). In addition, nifedipine, nitrendipine and nisoldipine (all at 10 μM) decreased protein synthesis in both cell types by 15–25%.
8. We concluded that cultured VSMC from TGR are hypertrophic in comparison with those from SD. This cell hypertrophy can be the consequence of the expression of the transgene Ren-2 that activates a tissular RAS and locally produces AII, which acts in a paracrine, autocrine, or intracrine manner. Cell hypertrophy in TGR cultures could be selectively reduced by RAS blockade, while nifedipine decreased cell size and protein synthesis in both hypertrophic and non hypertrophic cells.

     

糖尿病大鼠冠状动脉平滑肌细胞体外培养方法的探讨

目的探讨糖尿病大鼠冠状动脉平滑肌细胞体外培养方法,建立糖尿病大鼠冠状动脉平滑肌细胞模型,为糖尿病性冠心病的研究奠定基础。方法建立糖尿病大鼠模型,用酶消化法体外培养冠状动脉血管平滑肌细胞。结果糖尿病大鼠造模成功后分离冠状动脉,用酶消化法培养糖尿病大鼠血管平滑肌细胞,24h更换培养液液,培养7~10d细胞重叠生长达多层,高低起伏呈“峰—谷”状。细胞α-actin免疫组织化学染色鉴定为平滑肌细胞。结论糖尿病大鼠血管平滑肌细胞增殖速度快,培养条件要求严格,在形态学上与正常大鼠平滑肌细胞相同。     

丹皮酚对动脉粥样硬化家兔血管平滑肌细胞增殖的影响

目的研究丹皮酚对动脉粥样硬化家兔血管平滑肌细胞增殖的影响。方法高脂饮食法复制家兔动脉粥样硬化病理模型;HE染色并光镜观察主动脉病理学改变;MTT法分析体外培养的兔血管平滑肌细胞增殖水平;全自动生化分析仪测定主动脉组织中脂质含量;酶法测定SOD、MDA含量;放射免疫分析法测定IL-1β、TNF-α的含量;免疫组织化学法检测主动脉组织中PCNA的蛋白表达。结果丹皮酚(75、150 mg.kg-1)治疗给药(ig,6 wk)能减轻模型动物主动脉内膜增厚及泡沫细胞数量;使主动脉组织中脂质、脂质过氧化反应以及炎性细胞因子含量等方面得到显著改善;并能显著抑制主动脉组织中PCNA蛋白的表达强度;丹皮酚(100~300 mg.L-1)可明显抑制体外培养的血管平滑肌细胞增殖反应。结论丹皮酚对血管平滑肌细胞增殖有明显抑制作用,可能是其降脂、减轻脂质过氧化反应以及炎性细胞因子含量等协同作用结果,并可能通过抑制PCNA的表达而调控动脉粥样硬化病变中的血管平滑肌细胞增殖周期。     

亚硝基乙酰青霉胺抑制人血管平滑肌细胞增殖的实验研究

目的探讨亚硝基乙酰青霉胺对人血管平滑肌细胞(VSMC)增殖的抑制作用。方法将不同浓度的亚硝基乙酰青霉胺300、500、800、1000μmol/L作用于体外培养的血管平滑肌细胞(VSMC),采用氚-胸腺嘧啶核苷(3H-TdR)掺入的方法检测细胞的增殖。结果在500、800、1000μmol/L的亚硝基乙酰青霉胺作用下,VSMC的3H-TdR掺入量cpm分别为1096.33±85.60、852.00±57.80、693.00±49.60,均与对照组的1270.00±96.50有显著性差异(P<0.01),并表现为剂量依赖性(P<0.01)。结论亚硝基乙酰青霉胺能够抑制人VSMC的增殖,可能有防治经皮腔内冠状动脉成形术后再狭窄的作用。     

缬沙坦对人脐静脉平滑肌细胞凋亡的影响

目的:研究血管紧张素受体阻滞剂缬沙坦对人脐静脉血管平滑肌细胞(VSMC)凋亡的调节作用,以探讨缬沙坦抗动脉粥样硬化的作用机制.方法:荧光显微镜观察缬沙坦作用后VSMC凋亡的形态学变化,用流式细胞仪测定缬沙坦用药前后VSMC凋亡率并作周期分析,用流式细胞仪检测缬沙坦对凋亡相关基因Bax,Bcl-2和caspase3表达的影响.结果:缬沙坦高浓度 血管紧张素Ⅱ(AngⅡ)组的VSMC凋亡率较AngⅡ模型组明显提高,缬沙坦单药高、中、低浓度组的VSMC凋亡率较对照组明显提高.细胞周期分析表明,AngⅡ 缬沙坦组与AngⅡ组比较,G0/G1期百分率显著升高,S期百分率显著降低,且具有浓度依赖性.Bax和caspase 3基因经高浓度缬沙坦组作用24 h后表达水平增加,Bcl-2则没有改变.结论:缬沙坦对AngⅡ诱导VSMC的增殖有抑制作用;缬沙坦可能促进VSMC凋亡;缬沙坦促进VSMC凋亡可能与Bax和caspase基因表达增加有关.     

钩藤碱和异钩藤碱抑制血管紧张素Ⅱ诱导血管平滑肌细胞增殖及相关机制

目的探讨钩藤碱和异钩藤碱对血管紧张素Ⅱ诱导的血管平滑肌细胞增殖的抑制效应及相关机制。方法建立血管紧张素Ⅱ诱导血管平滑肌细胞增殖模型,通过四甲基偶氮唑盐比色法、流式细胞术和逆转录聚合酶链反应观察钩藤碱和异钩藤碱对其增殖活性、细胞周期、细胞膜AT1R蛋白表达、信号转导通路NF-κB和Stat3蛋白表达、原癌基因c-Myc和c-Fos蛋白表达与mRNA转录的影响。结果血管紧张素Ⅱ明显刺激血管平滑肌细胞增殖,钩藤碱和异钩藤碱呈剂量依赖性抑制血管紧张素Ⅱ诱导的血管平滑肌细胞增殖;在钩藤碱和异钩藤碱干预下,血管平滑肌细胞处于G0/G1期的细胞数明显增多,S期的细胞数明显减少,c-Myc、c-Fos、AT1R、NF-κB、Stat3的蛋白表达以及c-MycmRNA和c-FosmRNA转录也明显降低。结论钩藤碱和异钩藤碱对血管紧张素Ⅱ诱导血管平滑肌细胞增殖有明显抑制效应,其机制与阻滞血管平滑肌细胞G0/G1期向S期转化以及下调AT1R、NF-κB、Stat3、c-Myc、c-Fos蛋白的表达以及c-MycmR-NA和c-FosmRNA转录有关。     

粉防己碱促进和敏化肾性高血压大鼠血管平滑肌细胞凋亡

目的：从大鼠血管平滑肌细胞凋亡角度探讨粉防己碱逆转肾血管性高血压血管重构的机制。方法：两肾-夹法制备肾性高血压模型,原位末端标记法检测主动脉和尾动脉动脉壁平滑肌细胞凋亡数量;[3H]-TdR掺入和流式细胞术分析粉防己碱对培养细胞凋亡率的影响。结果：粉防己碱能够诱导血管平滑肌细胞凋亡,并使低血清和TNFα、转化生长因子（TGFβ1）诱导的细胞凋亡率增加。结论：粉防己碱逆转肾性高血压大鼠（RHR）血管重构的机制可能与诱导和敏化RHR血管平滑肌细胞凋亡有关。     

普伐他汀对溶血磷脂酰胆碱促血管平滑肌细胞增殖及细胞粘附的影响

目的　探讨羟甲基戊二酰辅酶A还原酶抑制剂普伐他汀对溶血磷脂酰胆碱 (LPC)促血管平滑肌细胞增殖及白细胞与内皮细胞粘附的影响。方法　用MTT法检测LPC对平滑肌细胞增殖的量效和时效关系及普伐他汀对LPC促平滑肌细胞增殖的影响 ;用直接记数法检测LPC诱导中性粒细胞系K5 6 2细胞与人脐静脉内皮细胞系ECV30 4细胞的粘附和普伐他汀对LPC所致白细胞与内皮细胞粘附的影响。结果　用 1～ 10 μmol·L-1LPC孵育血管平滑肌细胞 2 4～ 4 8h后 ,呈时间和剂量依赖性地诱导细胞增殖 ,而用 0 3～ 1mmol·L-1普伐他汀预孵育平滑肌细胞 1h ,再与 3μmol·L-1LPC共孵育 2 4～ 4 8h ,明显地抑制LPC所诱导的细胞增殖 ;用 3μmol·L-1LPC孵育ECV30 4细胞 12h显著增加K5 6 2细胞与ECV30 4细胞的粘附 ,而将ECV30 4细胞用 1mmol·L-1普伐他汀预处理后 ,明显减少白细胞与内皮细胞的粘附。结论　普伐他汀可抑制LPC促血管平滑肌细胞增殖及白细胞与内皮细胞粘附的作用。     

Interactions between cell death induced by statins and 7-ketocholesterol in rabbit aorta smooth muscle cells

BACKGROUND AND PURPOSE: 7-Ketocholesterol, an oxysterol present in atherosclerotic lesions, induces smooth muscle cell (SMC) death, thereby destabilizing plaques. Statins protect patients from myocardial infarction, though they induce SMC apoptosis. We investigated whether statins and 7-ketocholesterol exerted additive cell death effects. EXPERIMENTAL APPROACH: Cultured rabbit aorta SMCs (passage 2-6) were exposed to 7-ketocholesterol with or without fluvastatin, simvastatin or pravastatin. Uptake of neutral red (NR), monolayer protein, cleavage of the pan-caspase substrate Asp-Glu-Val-Asp-rhodamine110, cell morphology (light and electron microscopy) and processing of microtubule-associated protein 1 light chain 3 (LC3, immunoblot) were determined. KEY RESULTS: NR uptake declined upon 18 h exposure to 25 microM 7-ketocholesterol (-41+/-3%, n=13), 100 microM fluvastatin (-59%) or 30-100 microM simvastatin (-28 to -74%). Oxysterol and high statin concentrations exerted additive effects, but lower concentrations (fluvastatin 10-30 microM, simvastatin 1-10 microM) partly reversed viability loss. 7-Ketocholesterol caused intense cytoplasmic vacuolization, processing of LC3-I to LC3-II, but little caspase activation (increase 29.5%). Fluvastatin (10-100 microM, 70-545% increase) and simvastatin (3-100 microM 43-322% increase) induced caspase activation without LC3 processing, but failed to activate caspases in 7-ketocholesterol-treated SMCs. Pravastatin up to 100 microM was always inactive. CONCLUSIONS AND IMPLICATIONS: 7-Ketocholesterol caused SMC death, mainly via autophagic vesicle formation with LC3 processing, whereas lipophilic statins evoked SMC apoptosis. Cell death following 7-ketocholesterol and low statin concentrations were not additive, presumably because the autophagic process interfered with statin-induced caspase activation. This further illustrates that drug effects in normal SMCs are not necessarily predictive for activities in atherosclerotic settings.     

氧化甾醇诱导血管平滑肌细胞凋亡及其作用特点的研究

目的研究３β,５α,６β－胆甾烷二醇（Ｔｒｉｏｌ）诱导血管平滑肌细胞（ＶＳＭＣｓ）凋亡及其与２５－羟胆固醇（２５－ＯＨ）比较的特点。方法体外培养ＶＳＭＣｓ、光镜、透射电镜及ＴＵＮＥＬ技术。结果ＶＳＭＣｓ经Ｔｒｉｏｌ处理后,贴壁层细胞呈现核染色质浓集,核碎裂和凋亡小体形成等凋亡的超微结构变化;ＴＵＮＥＬ显示ＶＳＭＣｓ凋亡细胞数随Ｔｒｉｏｌ浓度的增加而增多;剂量为 ３０ μｍｏｌ·Ｌ－１的 Ｔｒｉｏｌ和 ２５－ＯＨ诱导 ＶＳＭＣｓ的凋亡作用,前者不能而后者能被 ５０ μｍｏｌ·Ｌ－１的胆固醇所抑制。结论Ｔｒｉｏｌ能诱导ＶＳＭＣｓ凋亡,不同氧化甾醇可能有不同的作用通道和机制;氧化甾醇诱导ＶＳＭＣｓ凋亡可能是引起动脉粥样硬化斑块破溃,导致急性心血管事件发生的机制之一。     

膦甲酸钠干预高磷诱导的血管平滑肌细胞钙化的研究

目的　观察不同浓度的膦甲酸钠 (PFA)对高磷诱导的牛主动脉血管平滑肌细胞钙沉积和骨钙素 (OC)表达的影响。方法　用不同磷浓度 (正常磷Pi1.5mmol·L-1、高磷Pi2 0mmol·L-1)及含不同浓度膦甲酸钠的培养液 ,体外培养牛主动脉平滑肌细胞 ,观察血管平滑肌细胞钙沉积及骨钙素表达。用甲ο 酚酞络合酮方法测定钙含量 ,BCA法测定蛋白含量。培养上清液中骨钙素浓度用放射免疫法测定 ,用蛋白含量标化钙含量、骨钙素的浓度 ,RT PCR观察骨钙素mR NA的表达。结果　①高磷组较正常磷组平滑肌细胞钙沉积增加 :细胞培养 6d后 ,高磷组 (77 187± 11 6 92 )mg·g-1Pro ,正常磷组 (2 5 76 8± 1 75 0 )mg·g-1Pro ,P <0 0 1;②膦甲酸钠能有效地抑制钙沉积 :培养 6d ,高磷 +PFA 1 0mmol·L-1组 (37 72 9± 5 899)mg·g-1Pro ,与高磷未干预组相比 ,P <0 0 1;③高磷组骨钙素表达明显增高。高磷组与正常磷组相比 ,培养上清液中骨钙素水平 :(1 5 0 3× 10 -2 ±2 6 0 1× 10 -3 )mg·g-1Pro对 (2 981× 10 -3 ± 8 382× 10 -4)mg·g-1Pro ,P <0 0 1;平滑肌细胞骨钙素mRNA表达 (OC/GAPDH) :1 886± 0 16 5对 0 75 2± 0 0 5 2 1,P <0 0 1;④膦甲酸钠能有效地抑制骨钙素的表达。高磷 +PFA 1 0mmol·L-1组与高磷组?     

Melatonin reduces peroxynitrite-induced injury in aortic smooth muscle cells

AIM:To study the protective role of melatonin (MT) in peroxynitrite-induced injury in cultured aortic smooth muscular cells (ASMC). METHODS: Peroxynitrite was synthesized chemically with a quenched flow reaction.Cells were exposed to peroxynitrite 500μmol/L for 1h in the absence or presence of various concentrations of MT 100, 300, and 500μmol/L. Nitrotyrosine (NT), a specific “footprint” of peroxynitrite formation, was detected by immunohistochemical technique. The DNA damage was assayed by TUNEL technique. The levels of MDA in the medium and cell viability were measured. RESULTS: Incubation of ASMC with peroxynitrite 500μmol/L for 1h elicited the increase in the extent of immunostaining for NT, the rate of the TUNEL-positive cell, the content of MDA in the medium, and the number of dead cell. Pretreatment of ASMC with MT 100-500μmol/L decreased these peroxynitrite-induced changes in a concentration-dependent manner. CONCLUSION: MT attenuated the injury induced by peroxynitrite in ASMC.     

家兔动脉血管平滑肌细胞培养方法的改进

目的提高家兔血管平滑肌细胞(vascular smooth mus-cle cell,VSMC)体外培养的成功率。方法以传统的主动脉平滑肌细胞培养方法中的组织块贴壁法为基础,从动物选择、培养基配制、血管取材、组织块的大小和接种间距、培养液的量及换液量、细胞传代的时机等多个重要环节进行改进;用倒置显微镜、电镜对培养细胞进行形态学观察,并用平滑肌细胞特异性α-肌动蛋白(α-actin)单克隆抗体免疫组织化学方法进行鉴定。结果台盼蓝检查传代细胞的存活率大于97%;光镜下见培养细胞平行排列呈长梭形及"峰、谷"样结构特征;免疫组织化学染色鉴定培养细胞中VSMC的纯度为97%;电镜技术观察到VSMC完整的超微结构。结论此培养方法能提高动脉平滑肌细胞原代培养的成功率,传代后血管平滑肌细胞生物学特征的稳定性好,可作为研究血管平滑肌细胞生物学行为的有效模型。     

尼莫地平对过氧化氢诱导猪脑基底动脉氧化应激损伤的保护作用

目的：探讨尼莫地平对过氧化氢（H2O2）诱导猪脑基底动脉损伤的保护作用。方法：采用去内皮离体血管环灌流的方法，建立H2O2损伤模型。比较正常对照组，H2O2（2×10^-4mol／L）损伤组，维生素C（10^-4mol／L）组，尼莫地平高、中、低剂量（5×10^-6、5×10^-7、5×10^-8mol／L）组血管环对KCl、苯肾上腺素的张力；检测各组血管组织匀浆中的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GSH—PX）活性及丙二醛（MDA）含量。结果：（1）H2O2损伤组与正常对照组比较，血管环对KCl、苯肾上腺素的收缩反应明显增加；尼莫地平高、中、低剂量组呈剂量依赖性抑制KCl、苯肾上腺素对血管环的收缩反应。（2）H2O2损伤组MDA含量升高，SOD、CAT、GSH—PX活性降低，与正常对照组比较，差异有统计学意义（P〈0．05）。尼莫地平高、中、低剂量均能降低组织中MDA含量，增强SOD、CAT、GSH-PX，的活性，与H2O2损伤组比较，差异有统计学意义（P〈0．05）。结论：钙通道阻断剂尼莫地平具有抗氧化应激作用，能预防H2O2对脑基底动脉血管的氧化损伤。     

Superoxide from NADPH oxidase upregulates type 5 phosphodiesterase in human vascular smooth muscle cells: inhibition with iloprost and NONOate

Background and purpose:

To determine whether there is an association between vascular NADPH oxidase (NOX), superoxide, the small GTPase Rac₁ and PDE type 5 (PDE5) in human vascular smooth muscle cell (hVSMCs).

Experimental approach:

hVSMCs were incubated with xanthine–xanthine oxidase (X-XO; a superoxide generating system) or the thromboxane A₂ analogue, U46619 (±superoxide dismutase (SOD) or apocynin) for 16 h. The expression of PDE5 and NOX-1 was assessed using Western blotting and superoxide measured. The role of Rac₁ in superoxide generation was assessed by overexpressing either the dominant-negative or constitutively active Rac isoforms. The effects of iloprost, DETA-NONOate and the Rho-kinase inhibitor, Y27632, on PDE5 and NOX-1 expression were also studied.

Key results:

Following 16 h incubation, U46619 and X-XO promoted the expression of PDE5 and NOX-1, an effect blocked by SOD or apocynin when co-incubated over the same time course. X-XO and U46619 both promoted the formation of superoxide. Overexpression of dominant-negative Rac₁ or addition of iloprost, DETA-NONOate or Y27632 completely blocked both superoxide release and PDE5 protein expression and activity.

Conclusions and implications:

These data demonstrate that superoxide derived from NOX upregulates the expression of PDE5 in human VSMCs. As PDE5 hydrolyses cyclic GMP, this effect may blunt the vasculoprotective actions of NO.