高同型半胱氨酸对高血压大鼠血管平滑肌细胞GRP78和CHOP的表达的影响与血管重构的关系

目的：观察同型半胱氨酸（Homocysteine,Hcy）对高血压大鼠内质网应激因子GRP78和CHOP表达及血管中层厚度变化,探讨Hcy对血管重构的影响。方法：采用腹主动脉缩窄术建立高血压大鼠模型,术后两周采用无创尾套法测量大鼠血压,选取24只成年雄性大鼠[平均动脉压（MAP）〉150mmHg]随机等分为2组,即对照组和蛋氨酸组,每组12只（n=12）。对照组给予普通饮食＋双蒸水灌胃,蛋氨酸组给于30g/L蛋氨酸饮食＋双蒸水灌胃;根据实验结束的时间,又将各组分为4W和8W两个亚组,各亚组6只（n=6）。用同型半胱氨酸检测仪检测血清同型半胱氨酸浓度,用颈动脉插管法测定各组大鼠的MAP,并利用图像分析软件测量血管中层的厚度;HE染色观察大鼠主动脉血管形态学变化;通过免疫组化及Western blot检测大鼠主动脉血管平滑肌细胞（VSMCs）组织中GRP78及CHOP表达水平。结果：①对照组大鼠血清Hcy浓度在正常值范围（〈10μmol／L）;蛋氨酸组大鼠血清Hcy浓度明显高于对照组（P〈0．01）。②两组大鼠MAP均显著增高,4周时两者之间差异不明显,8周时两者差异显著（P〈0．05）;③蛋氨酸组大鼠血管平滑肌中层厚度显著大于对照组（P〈0．05）;④HE染色显示,与对照组相比,蛋氨酸组大鼠主动脉VSMCs显著肥大,管壁显著增厚;⑤两组CRP78和CHOP蛋白表达量增高,与对照组相比蛋氨酸组表达更明显。结论：高同型半胱氨酸可能通过促使高血压大鼠动脉VSMCs内质网应激反应,导致CRP78及CHOP的平衡失调加剧,从而引起血管损伤加重,而发生血管重构加重。     

高血压大鼠心肌内质网应激时GRP78和CHOP的表达及其与心肌细胞凋亡的关系

目的:探讨心肌组织内质网应激相关因子葡萄糖调节蛋白78(glucose-regulated protein78,GRP78)和C/EBP环磷酸腺苷反应元件结合转录因子同源蛋白(C/EBP homologous protein,CHOP)在高血压大鼠心肌中的表达及其与心肌细胞凋亡的关系。方法:将48只SD大鼠随机等分为两个组,一组采用腹主动脉缩窄术(TAC)建立高血压模型,称为TAC组;另一组只进行相应的假手术,称为Sham组。按术后饲养时间(3 d、7 d、14 d和28 d)的不同,TAC组又分为4个组,即TAC3d组、TAC7d组、TAC14d组和TAC28d组,每组6只(n=6);Sham组也又分为4个组,即Sham3d组、Sham7d组、Sham14d组和Sham28d组,每组6例(n=6)。用颈动脉插管法测定各组大鼠的平均动脉压(MAP);用Western blot法检测GRP78蛋白和CHOP蛋白表达的水平;用TUNNEL法检测心肌细胞的凋亡。结果:①TAC3d组、TAC7d组、TAC14d组和TAC28d组的MAP均显著高于相应的各Sham组(P0.05),且TAC各组的MAP随着术后时间的延长,血压值呈逐渐递增的趋势。②GRP78蛋白在TAC术后3 d即发现表达(0.20±0.02),明显高于Sham3d组(0.10±0.02)(P0.05);但明显低于其他各TAC组(P0.05)。随着术后时间的延长,TAC7d组GRP78蛋白的表达达到最高(0.94±0.03),其后各组呈递减趋势;但TAC7d组、TAC14d组和TAC28d组GRP78蛋白表达的水平均明显高于相应的各Sham组(P0.05)。③随着TAC术后时间的延长,心肌组织中CHOP蛋白的表达呈递増趋势;TAC7d组、TAC14d组和TAC28d组CHOP蛋白表达的水平,分别为(0.17±0.01)、(0.36±0.03)和(0.61±0.02),均明显高于相应的各Sham组(P0.05)。TAC3d组CHOP蛋白的表达与Sham3d组比较,无明显差异。④Sham3d组和TAC3d组中仅有极少数凋亡细胞;Sham7d组和TAC7d组可见较多的凋亡细胞,且随着时间的延长细胞凋亡率逐渐增加,TAC28d组的凋亡率达最高(30.23±0.17)%;TAC7d组、TAC14d组和TAC28d组细胞凋亡率显著高于相应的各Sham组(P0.05)。⑤相关性分析显示,从TAC7d组、14d组及28d组的MAP与心肌组织中GRP78蛋白的表达呈显著的负相关(r=-0.882,P0.01),与CHOP蛋白的表达呈显著正相关(r=0.933,P0.01);CHOP蛋白的表达与GRP78蛋白的表达呈显著负相关(r=-0.980,P0.01),与心肌细胞的凋亡率呈显著的正相关(r=0.997,P0.01)。结论:高血压诱导心肌组织内质网应激反应在血压升高早期以GRP78的表达占优势,随着血压持续性升高可导致CHOP在心肌中超表达,参与心肌细胞凋亡的病理过程,并使心肌内质网应激稳态调节发生失衡。     

HIP-55介导血管紧张素Ⅱ诱导的血管胶原沉积

目的探究HIP-55是否介导血管紧张素Ⅱ诱导的血管胶原沉积。方法生物信息学分析的方法预测HIP-55是否参与血管紧张素Ⅱ(AngⅡ)诱导的血管重构,小鼠背部皮下埋入AngⅡ(1 mg·kg~(-1)·d~(-1))微量泵14 d诱导血管重构模型,利用无创血压仪检测小鼠血压变化,蛋白质印迹法(Western blot)、反转录聚合酶链式反应(RT-PCR)检测HIP-55在血管重构模型中的表达变化情况。并构建HIP-55基因敲除小鼠,将小鼠分为4组:野生/假手术组(WT/Sham组)、HIP-55基因敲除/假手术组(HIP-55~(-/-)/Sham组)、野生/埋泵组(WT/AngⅡ组)和HIP-55基因敲除/埋泵组(HIP-55~(-/-)/AngⅡ组),主动脉苏木素-伊红(HE)染色,Masson染色检测血管形态变化及胶原沉积变化。结果生物信息学提示HIP-55可能参与AngⅡ诱导的血管重构。与对照组相比,实验组小鼠血管胶原沉积显著增加(3.1±0.18比1.1±0.04,P<0.01)、血管横切平均面积显著增加(2.7±0.1比1.0±0.04,P<0.01)、平均厚度明显增加[(105.7±7.0)μm比(66.0±7.6)μm,P<0.01]、平均厚度/内径明显增加(0.28±0.01比0.17±0.01,P<0.01)。实验组小鼠血管中HIP-55 mRNA(1.6±0.22比1.0±0.03,P<0.01)和HIP-55蛋白(1.6±0.15比1.0±0.04,P<0.01)表达水平均明显增加。与WT/Sham组相比,HIP-55~(-/-)/Sham组小鼠的血管胶原沉积水平无明显变化(1.1±0.04比1.0±0.05,P=0.70);给予AngⅡ埋泵后,与WT/AngⅡ组相比,HIP-55~(-/-)/AngⅡ组小鼠的血管胶原沉积明显减少(2.6±0.2比3.3±0.1,P<0.05)。结论 HIP-55介导AngⅡ诱导的血管胶原沉积。     

运动训练对大鼠脑缺血再灌注后神经细胞内质网应激的影响

目的探讨运动训练对大鼠脑缺血再灌注后神经细胞内质网应激的影响。方法清洁级SD大鼠100只,采用随机数字表法将SD大鼠分为正常对照组、假手术组、模型组和实验组,每组25只。造模成功后,实验组进行功能训练。于造模后1、3、7、14、28 d,分别处死5只大鼠,取脑组织,采用TUNEL检测神经细胞凋亡情况,采用RT-CPR和Western印迹法检测葡萄糖调节蛋白(GRP)78、C/EBP同源蛋白(CHOP)和Tribbles相关蛋白(TRB)3表达水平。结果缺血再灌注后1、3、7、14、28 d,实验组凋亡细胞数明显少于模型组(P<0.05)。缺血再灌注后1、3、7、14、28 d,实验组和模型组GRP78、CHOP和TRB3 mRNA和蛋白表达水平均显著高于假手术组(P<0.05);缺血再灌注后3 d、7 d、14 d、28 d,实验组大鼠脑组织GRP78、CHOP和TRB3 mRNA和蛋白表达水平显著低于模型组(P<0.05)。结论运动训练能明显抑制脑缺血再灌注后神经细胞凋亡,机制可能主要通过下调脑组织GRP78、CHOP和TRB3表达水平实现的。     

高血压大鼠血管平滑肌细胞GRP78和caspase-12表达的变化及依那普利的干预作用

目的:观察高血压大鼠动脉血管平滑肌细胞（VSMCs）内质网应激（ERS）相关因子葡萄糖调节蛋白78（GRP78）和半胱氨酸门冬氨酸特异性蛋白酶12（caspase-12）表达的变化,并探讨高血压时VSMCs中ERS的分子机制,以及依那普利（enalapril,Ena）对血管重构的影响。方法: 将40只健康雄性SD大鼠随机分为4组,即假手术（sham）组、sham+Ena组,腹主动脉缩窄术（AAB）组及AAB＋Ena组,每组10只。4周后,通过颈动脉插管法测定大鼠血压和利用图像分析系统测量大鼠主动脉中层的厚度,并通过免疫组化染色法检测GRP78和caspase-12的表达。结果: ①AAB组大鼠的平均动脉压（MAP）显著高于sham组、sham+Ena组和AAB＋Ena组（P<0.05）。②AAB组大鼠血管平滑肌中层厚度显著大于sham组、sham+Ena组和AAB＋Ena组（P<0.05）。③AAB组大鼠GRP78和caspase-12的表达量明显高于sham组、sham+Ena组和AAB＋Ena组大鼠。结论: AAB所致的高血压可触发动脉血管平滑肌细胞过长过强的ERS 。Ena可能通过下调ERS的水平,逆转高血压所致VSMCs损伤的作用,对VSMCs具有保护作用。其作用机制可能与其降低caspase-12介导的ERS反应有关     

酸性环境对高磷诱导的大鼠血管平滑肌细胞钙化的影响及机制研究

目的探讨酸性环境对高磷诱导的大鼠血管平滑肌细胞(VSMCs)钙化的影响及可能机制。方法体外分离培养大鼠VSMCs,采用免疫细胞化学方法鉴定。将VSMCs按随机数字表法分为正常对照组、高磷+p H7.4、高磷+p H7.1和高磷+p H6.8(在高磷培养基的基础上调整p H值为6.8、7.1和7.4三个亚组)。刺激4 d后,采用RT-PCR检测L型钙通道(LTCC)α_(1C)、β_2和β_3亚基,Runt相关转录因子2(Runx2)及Smad1基因的表达;应用钙离子探针Fluo-3/AM检测VSMCs胞外钙离子内流的效应变化。刺激14 d后,对各组细胞进行钙化染色、钙含量和碱性磷酸酶(ALP)活性测定。结果与正常对照组比较,高磷+p H7.4组钙含量、ALP活性、Runx2和Smad1mRNA的表达明显增高(88.26±6.43比22.39±3.19、94.33±3.08比20.39±1.18、0.37±0.02比0.01±0.00、0.65±0.05比0.07±0.01,均为P<0.05);与高磷+p H7.4组比较,高磷+p H7.1组和高磷+p H6.8组的钙含量、ALP活性、Runx2和Smad1mRNA的表达均降低(69.95±1.72和50.74±3.29、51.11±2.05和34.62±1.13、0.25±0.02和0.09±0.01、0.44±0.04和0.23±0.01,均为P<0.05)。与正常对照组比较,高磷+p H7.4组的LTCCβ_3亚基mRNA表达水平增加(0.80±0.01比0.34±0.13,P<0.01),高磷+p H7.1组和高磷+p H6.8组的LTCCβ_3亚基mRNA表达水平均下降(0.64±0.11和0.43±0.01,均为P<0.01)。各组之间LTCCα_(1C)和β_2亚基mRNA的表达差异无统计学意义(P=0.08和0.74)。与正常对照组比较,高磷+p H7.4组的VSMCs胞内钙离子浓度增加(438.33±7.50比149.54±20.89,P<0.05);高磷+p H7.1组和高磷+p H6.8组的VSMCs胞内钙离子浓度均降低(329.66±16.64和234.00±17.43,均为P<0.01)。结论酸性环境可以抑制高磷诱导的大鼠VSMCs钙化,其可能是通过抑制LTCCβ_3亚基表达,降低VSMCs钙离子内流,阻滞VSMCs发生表型转化来实现的。     

缝隙连接在维持血管张力及损伤血管修复中的作用

目的探讨缝隙连接在维持血管张力及损伤血管修复中的作用。方法取大鼠主动脉制成血管环分别测量在18α-甘草次酸(18α-GA)作用前后血管环对去甲肾上腺素(NE)和乙酰胆碱(Ach)反应性变化;建立大鼠颈动脉损伤模型,给予生胃酮3 mg/(kg·d)腹腔注射,对照组给予生理盐水腹腔注射(2 m L/d),14天后处死动物,用HE和DAPI-伊文思蓝染色观察新生内膜厚度,细胞免疫荧光染色法及Western blot检测靶血管缝隙连接蛋白43(Cx43)的表达。结果单纯给予18α-GA处理血管环并未出现明显的收缩或舒张反应。对照组给予去甲肾上腺素或乙酰胆碱后血管环发生明显的收缩或舒张反应,而经18α-GA预处理后,去甲肾上腺素或乙酰胆碱引起的血管环收缩或舒张反应显著降低(去甲肾上腺素:0.60±0.03比0.21±0.04;乙酰胆碱:0.15±0.01比0.62±0.03; P0.05)。损伤2周生胃酮干预组血管新生内膜增生明显减少,血管腔狭窄减轻。生胃酮干预组新生内膜细胞核数量显著低于对照组(89±28比236±15,n=5,P0.01)。免疫荧光染色显示,在形成的新生内膜中Cx43表达丰富。Western blot结果显示,生胃酮干预组Cx43的表达显著低于对照组(0.38±0.11比0.93±0.06,n=3,P0.01)。结论缝隙连接在生理条件下参与维持及调节血管张力,在病理条件下能够促进血管损伤后新生内膜的过度增生,在血管损伤性疾病的发生、发展过程中具有重要作用。     

去天门冬氨酸血管紧张素Ⅰ减轻大鼠心肌微血管内皮细胞缺血/再灌注损伤

目的探讨去天门冬氨酸血管紧张素Ⅰ(DAA-Ⅰ)对大鼠心肌微血管内皮细胞(CMECs)缺血/再灌注损伤的影响。方法分离培养大鼠CMECs,建立模拟缺血/再灌注模型,完全随机分组,分为对照组、模拟缺血/再灌注组(SI/R组)、模拟缺血/再灌注+DAA-Ⅰ(2.5、3.75、5.0μmol/L)组。MTT检测细胞增殖能力,细胞划痕实验检测细胞迁移能力,TUNEL法检测细胞凋亡,采用Western blot检测GRP78/Bip、CHOP/GADD153、pro-caspase-12、cleaved-caspase-12蛋白的表达。结果与对照组相比较,SI/R组CMECs增殖能力明显降低(P<0.01),凋亡率显著上升(24.85%±0.67%比3.55%±0.11%,P<0.01)。与SI/R组相比,SI/R+DAA-Ⅰ组细胞增殖能力明显升高(P<0.01)并呈剂量依赖性,细胞迁移率上升(P<0.01)并呈剂量依赖性,凋亡率明显下降(15.18%±0.40%比24.85%±0.67%,P<0.01)并呈剂量依赖性。与对照组相比较,SI/R组和SI/R+DAA-Ⅰ组的GRP78、CHOP/GADD153、cleaved-caspase-12表达明显上升(均为P<0.01)。与SI/R组相比,SI/R+DAA-Ⅰ组的GRP78、CHOP/GADD153、cleaved-caspase-12表达明显降低(均为P<0.01)。结论 DAA-Ⅰ可显著抑制缺血/再灌注损伤诱导的CMECs凋亡,促进CMECs存活,改善细胞功能,其保护作用可能与下调ERS相关蛋白的表达有关。     

小干扰RNA对川崎病血清诱导血管内皮细胞基质金属蛋白酶-9表达的影响

目的 观察川崎病急性期血清对血管内皮细胞摹质金属蛋白酶-9(MMP-9)表达的影响以及MMP-9小干扰RNA(siRNA)对上述过程的调节作用.方法 构建MMP-9 siRNA质粒,脂质法转染血管内皮细胞(ECV-304).ECV-304细胞培养分为川崎病血清+siRNA阴性对照组、正常血清组、川崎病血清+MMP-9 siRNA1组、川崎病血清+MMP-9 siRNA2组、川崎病血清+人血丙种球蛋白组、川崎病血清组.应用逆转录聚合酶链式反应检测MMP-9 mRNA的表达,免疫印迹法检测MMP-9蛋白的表达.结果 川崎病血清组和川崎病血清+siRNA阴性对照组的MMP-9 mRNA、MMP-9蛋白表达分别是2.49±0.03、1.20±0.04和2.45±0.03、1.15±0.03,均较正常血清组(1.21±0.03、0.52±0.03)明显增高(均P<0.01).川崎病血清+MMP-9 siRNA1组(0.78±0.03、0.31±0.02)、川崎病血清+MMP-9 siRNA2组(0.74±0.04、0.28±0.04)及川崎病血清+人血丙种球蛋白组(1.58±0.03、0.88±0.04)的MMP-9 mRNA、MMP-9蛋白表达与川崎病血清组及川崎病血清+siRNA阴性对照组比较均明显减少(均P<0.01).结论 川崎病急性期血清能诱导血管内皮细胞的MMP-9表达增高,可能参与川崎病冠状动脉损伤的发生.构建的MMP-9 siRNA能显著抑制MMP-9 mRNA和蛋白的表达.     

小檗碱对家兔颈动脉粥样硬化组织核因子кB、血管细胞粘附分子1及单核细胞趋化蛋白1表达的影响

目的探讨小檗碱预防家兔颈动脉粥样硬化形成的作用机制。方法将24只大白兔随机分为正常对照组、模型组和小檗碱组。正常对照组给予普通饮食,模型组和小檗碱组给予高脂饲料喂养1周后行右侧颈动脉内膜空气干燥术,术后继续高脂饲料喂养4周以制成颈动脉粥样硬化模型,小檗碱组在给予高脂饲料喂养的同时每日灌服小檗碱。第5周麻醉处死,取右侧颈动脉组织行HE染色观察颈动脉病理改变,行免疫组织化学染色检测核因子кB的活性,逆转录聚合酶链反应检测核因子кBp65、血管细胞粘附分子1和单核细胞趋化蛋白1mRNA表达水平。结果模型组颈动脉血管内膜明显增生,内膜下和中膜可见大量泡沫细胞堆积,有明显的动脉粥样硬化斑块形成;而小檗碱组的内膜轻度增厚,内膜下有少量泡沫细胞形成。小檗碱组核因子кBp65阳性细胞数高于正常对照组(19.58±2.60比2.00±0.93,P<0.01),但明显低于模型组(37.50±2.45,P<0.01)。小檗碱组核因子кBp65mRNA(0.42±0.05)、血管细胞粘附分子1mRNA(0.61±0.11)和单核细胞趋化蛋白1mRNA(0.57±0.18)的表达高于正常对照组(分别为0.18±0.04、0.20±0.04和0.33±0.05,P<0.01),但明显低于模型组(分别为0.66±0.16、0.81±0.11和0.76±0.03,P<0.01)。核因子кB的活性与血管细胞粘附分子1和单核细胞趋化蛋白1的mRNA表达量明显相关(r=0.926,P<0.01;r=0.958,P<0.01)。结论小檗碱可能通过抑制核因子кB活性以及降低血管细胞粘附分子1和单核细胞趋化蛋白1的表达而预防家兔颈动脉粥样硬化。     

Effects of adrenomedullin on vascular calcification in rats

OBJECTIVE: The aim of the present study was to investigate the effect of adrenomedullin (ADM) on vascular calcification. METHODS: The vascular calcification model was established in rats (VND group) by using vitamin D3 (300,000 IU/kg) and nicotine (25 mg/kg, two doses). The effect of liposome-encapsulated ADM was observed. Vascular calcium content, alkaline phosphatase (ALP) activity, ADM in aortic tissue and plasma, binding ability of 125I-ADM for ADM receptor on vascular plasma membrane and content of cAMP in vessels were measured. RESULTS: Compared with control rats, the aortic calcium content and vascular ALP activity in rats of the VDN group was obviously increased; in addition ADM concentrations in plasma and vessels of rats in VDN group were increased. But the maximum binding sites of 125I-ADM for ADM receptor (Bmax) on vascular plasma membrane in rats of VDN group were significantly decreased compared with control rats. The affinity of 125I-ADM for the ADM receptor was reduced, as shown by the Kd value and vascular cAMP content being reduced in rats of the VDN group compared to the control group. The in vitro response of isolated vessels to ADM incubation was weakened. Administration of empty liposome had no effect on vascular calcification. But administration of ADM significantly decreased vascular calcium content and ALP activity. The Bmax of 125I-ADM for ADM receptors on vascular plasma membrane increased by 17.7% (p < 0.01), and the value of Kd decreased by 36.2% (P < 0.01) in rats treated with ADM as compared with rats of the VDN group. In addition, the vascular cAMP content and the response to ADM in isolated aorta were markedly increased. CONCLUSION: Vascular calcification induced an alteration of the vascular ADM-ADM receptor-cAMP pathway. Treatment with exogenous ADM inhibited vascular calcification by improving the vascular ADM-ADM receptor-cAMP pathway.     

硫化氢对自发性高血压大鼠血管炎症反应的调节作用

目的 探讨新型气体信号分子硫化氢(H2S)对自发性高血压大鼠(SHR)血管炎症反应的调节作用.方法 4周龄Wistar-Kyoto(WKY)雄性大鼠和SHR雄性大鼠分为4组:WKY大鼠对照组、SHR对照组、SHR+硫氢化钠(NaHS,H2S供体)组及SHR+炔丙基甘氨酸(PPG,H2S生成关键酶抑制剂)组,饲养至9周.尾容积法测清醒时大鼠血压,免疫组织化学方法检测主动脉内皮细胞膜细胞间黏附分子-1(ICAM-1)、核转录因子-κB p65(NF-κB p65)和核转录因子抑制因子-α(IκB-α)的蛋白表达,原位杂交分析检测主动脉内皮细胞ICAM-1 mRNA的表达.结果 SHR对照组血压显著高于WKY对照组(P<0.05),主动脉内皮细胞ICAM-1、ICAM-1 mRNA、胞核NF-κB p65明显高(P均<0.01),胞浆IκB-α蛋白表达明显低(P<0.01).SHR+NaHS组血压显著低于SHR对照组,主动脉内皮细胞ICAM-1、ICAM-1 mRNA、胞核NF-κB p65蛋白表达明显低(P<0.05),胞浆IκB-α蛋白表达明显增高(P<0.05),SHR+PPG组主动脉内皮细胞ICAM-1、ICAM-1mRNA、胞核NF-κB p65蛋白表达更高(P<0.05),胞浆IκB-α蛋白表达显著低(P<0.05).结论 H2S可通过抑制SHR血管炎症发挥抗高血压效应.H2S的抗血管炎症效应可能通过上调IκB-α的表达,降低NF-κB p65的表达,抑制ICAM-1 mRNA的转录和蛋白表达实现.     

肾上腺髓质素对大鼠血管钙化的影响

目的　观察肾上腺髓质素 (ADM)对血管钙化的影响。方法　维生素D3 (VitD3 )和尼古丁制备大鼠血管钙化模型 ,分别测定血管、心肌钙含量和血管碱性磷酸酶 (ALP)活性 ,血浆和血管ADM含量 ,12 5I ADM与ADM受体的结合力及血管环磷酸腺苷 (cAMP)含量。结果　与对照组相比 ,钙化组 (VDN组 )的血管钙含量和ALP活性明显升高 ;血管及血浆ADM的含量亦升高 ,但12 5I ADM与血管质膜ADM受体结合的位点减少 ,Kd值升高 ,提示亲合力降低 ,同时伴钙化血管的cAMP合成减少。提示钙化血管对ADM的反应减弱。空载脂质体对血管钙化无影响。用脂质体包裹ADM组 (VDN ADM组 )与钙化组相比 ,其血管的钙含量、ALP的活性均明显降低 ;12 5　I ADM与血管质膜ADM受体结合的位点增加 ,Kd值减少 ,cAMP的合成也增加 ,提示该组血管对ADM的反应增强。结论　血管钙化时ADM ADM受体 cAMP途径发生变化 ,外源性ADM通过改善ADM ADM受体 cAMP途径 ,发挥抑制血管钙化的作用     

Subpressor angiotensin II is a bifunctional growth factor of vascular muscle in rats.

OBJECTIVE: The proposition that angiotensin II in subpressor does stimulates vascular growth in vivo was tested. DESIGN: Young adult, male Sprague-Dawley rats received angiotensin II, 200 ng/kg per min intraperitoneally by osmotic minipump, for 24 h or 7-10 days. Sham-infused rats served as controls. METHODS: Protein (35S-methionine) synthesis in aortic media, portal vein, bladder wall and diaphragm; proteoglycan (35S-sulfate) synthesis in aorta and bladder and synthesis of DNA (3H-thymidine) in aortic media were all measured ex vivo in the rat. RESULTS: The systolic blood pressure of angiotensin II-treated rats was unchanged at 24 h and increased at 7-10 days. At 24 h in angiotensin II-treated rats the protein synthesis in aortic media, portal vein and bladder wall but not in the diaphragm was increased, indicating that the hypertrophic effect of angiotensin II was independent of the arterial pressure. The rate of 35S-methionine washout from angiotensin II- and sham-treated aorta was the same. At 24 h there was also an increase in proteoglycans synthesis of the aorta and bladder wall of angiotensin II-treated rats. In contrast to protein synthesis, the incorporation of 3H-thymidine into aortic muscle DNA was reduced in angiotensin II-treated rats at 24 h, suggesting the inhibition of DNA synthesis. At 7-10 days angiotensin II administration the protein synthesis of aortic media returned to baseline, and DNA synthesis was bimodal: in 53% of rats (n = 10) inhibition continued, and in 26% (n = 5) it was increased by two- to threefold. CONCLUSIONS: The present findings confirm in vivo the bifunctionality of the trophic vascular action of angiotensin II. Vascular hypertrophy may play a role in the slow pressor action of angiotensin II.     

The effects of Xuezhikang on vascular remodeling and aortic fibers in spontaneously hypertensive rats

Background Xuezhikang is a traditional Chinese medicine for the therapy of patients with cardiovascular diseases. However, the effect of Xuezhikang on vascular remodeling and aortic fibers in spontaneously hypertensive rats remains unclear. Methods Thirty spontaneously hypertensive rats(SHRs) aged 8 weeks were randomized into three groups: SHRs control group(SHRs group, n = 10), group treated with low dose Xuezhikang(XZK-L,20 mg/kg/d, n = 10) and group treated with high dose Xuezhikang(XZK-H, 200 mg/kg/d, n = 10). The normal group was comprised of ten Wistar-Kyoto(WKY) rats of the same age. While under pentobarbital anesthesia, in vivo aortic stiffness was determined by a pulse wave velocity(PWV) technique and measured locally in the descending thoracic aorta by Doppler ultrasound echocardiography. Fixed tissues were sectioned and stained with hematoxylin and eosin, masson trichrome, aldehyde-fuchsin and Gordon-Sweets stain. Results The PWV, thicknesses of the aortic wall, wall-to-lumen(W/L) ratio, elastic fibers thicknesses and collagen volume fraction were measured. XZK-L and XZK-H groups were observed to be significantly greater than those in the normal group(P 0.01). The levels of PWV, W/L ratio and collagen fibers were observed to be significantly reduced in the XZK-H group when compared with the control group(P 0.05). There was no significance in reticular fiber distributing between the XZK-treated group and SHR group. The reticular fibers in SHR rats were obviously more than those of WKY rats. Conclusion The hypertensive vascular remodeling is associated with changes of elastic fibers and collagen and reticular fibers. Xuezhikang improves hypertensive vascular remodeling by repairing the elastic fibers and inhibiting the levels of collagen.     

Altered growth and lack of responsiveness to angiotensin II in aortic vascular smooth muscle cells from cirrhotic rats

BACKGROUND & AIMS: In cirrhosis, increased amounts of circulating hormones such as angiotensin II may induce vascular tone changes and alter vascular smooth muscle cell (VSMC) function and growth. The aim of this study was to investigate the growth of aortic VSMCs from cirrhotic rats with or without the addition of angiotensin II and to determine whether angiotensin II binding was preserved in cirrhotic VSMCs. METHODS: Cirrhosis was induced by bile duct ligation. Cell growth was studied in cultured aortic VSMCs at passage levels between 4 and 16 by determining cell number and protein synthesis. RESULTS: Proliferation rates of cirrhotic VSMCs were lower than those of control VSMCs. The addition of angiotensin II to control VSMCs caused an increase in cell proliferation and protein synthesis. This increase was not observed in cirrhotic cells. There were more angiotensin II receptors in cirrhotic than in control VSMCs, but no significant changes in affinities were found. Angiotensin II-stimulated protein synthesis was dependent on protein kinase C activity and increased intracellular Ca2+ concentrations. CONCLUSIONS: This study shows abnormalities in growth characteristics and responsiveness to angiotensin II of cultured aortic VSMCs from rats with cirrhosis. (Gastroenterology 1997 Jun;112(6):2065-72)     

Zidovudine-induced alterations in the heart and vascular smooth muscle of the rat

OBJECTIVE: We investigated the effects of zidovudine (AZT) on cardiac and vascular smooth muscle function and morphology in rats. METHODS: Four adult male Wistar-Kyoto rats received AZT in drinking water for 240 days; four rats served as controls. Echocardiographic examination and systolic blood pressure (SBP) measurement were performed. At the end of treatment the rats were sacrificed, their hearts were weighed and vascular smooth muscle contractile and relaxing properties were evaluated in vitro on endothelium-intact aortic rings. Morphological studies were performed on cardiac and aortic myocytes by light and electron microscopy. RESULTS: AZT-treated rats (AZT-Rs) showed higher SBP, greater heart weight and, as revealed by echocardiography, greater interventricular septum thickness. Electron microscopy revealed mitochondrial swelling in myocardiocytes in AZT-Rs. Reduced response to contractile stimuli and enhanced relaxation in response to charbacol were observed in the aortic rings of AZT-Rs. The aortic myocytes of AZT-Rs contained apparently unaffected ultrastructural features, but light microscopy suggested their marked enlargement. CONCLUSIONS: AZT treatment for 240 days in rats induces a modest increase in SBP, hypertrophy of the interventricular septum and modified vascular smooth muscle responsiveness. The role of mitochondria in these AZT-induced cardiovascular alterations remains to be established.     

Effects of adrenomedullin on vascular calcification in rats

Objective The aim of the present study was to investigate the effect of adrenomedullin (ADM) on vascular calcification. Methods The vascular calcification model was established in rats (VND group) by using vitamin D₃ (300000IU/kg) and nicotine (25mg/kg, two doses). The effect of liposome-encapsulated ADM was observed. Vascular calcium content, alkaline phosphatase (ALP) activity, ADM in aortic tissue and plasma, binding ability of ¹²⁵I-ADM for ADM receptor on vascular plasma membrane and content of cAMP in vessels were measured. Results Compared with control rats, the aortic calcium content and vascular ALP activity in rats of the VDN group was obviously increased; in addition ADM concentrations in plasma and vessels of rats in VDN group were increased. But the maximum binding sites of ¹²⁵I-ADM for ADM receptor (Bmax) on vascular plasma membrane in rats of VDN group were significantly decreased compared with control rats. The affinity of ¹²⁵I-ADM for the ADM receptor was reduced, as shown by the Kd value and vascular cAMP content being reduced in rats of the VDN group compared to the control group. The in vitro response of isolated vessels to ADM incubation was weakened. Administration of empty liposome had no effect on vascular calcification. But administration of ADM significantly decreased vascular calcium content and ALP activity. The Bmax of ¹²⁵I-ADM for ADM receptors on vascular plasma membrane increased by 17.7% (p<0.01), and the value of Kd decreased by 36.2% (P<0.01) in rats treated with ADM as compared with rats of the VDN group. In addition, the vascular cAMP content and the response to ADM in isolated aorta were markedly increased. Conclusion Vascular calcification induced an alteration of the vascular ADM-ADM receptor-cAMP pathway. Treatment with exogenous ADM inhibited vascular calcification by improving the vascular ADM-ADM receptor-cAMP pathway.