血管紧张素II及其受体在血管平滑肌细胞迁移中的作用

目的:探讨血管紧张素II(AngII)及其受体(ATRs)在局部血管损伤后血管平滑肌细胞(VSMC)迁移中的作用及其机制。方法:以体外培养VSMC为基础,采用细胞化学和改良Boyden'schamber的方法,观察AngⅡ干预VSMC后AngII受体的表达、VSMC迁移能力的变化、肌动蛋白纤维丝的动态组装变化,并探讨AT₁R拮抗剂、AT₂R拮抗剂对上述观测指标的影响。结果:AngII10^-7mol/L可以刺激VSMC发生迁移,该作用是通过影响VSMC内应力纤维动态组装而实现的;AngII干预VSMC后可使AT₁R表达上调,随着作用时间延长AT₁R表达水平下降。AT₁R拮抗剂可下调AT₁R表达。AngII通过AT₁R的介导发挥其影响VSMC迁移能力的生物学效应。AT₂R对此无明显影响。结论:AngII通过AT₁R介导来调节VSMC内肌动蛋白微丝的动态组装,进而改变VSMC的迁移能力,从而发挥其介导VSMC迁移的生物学效应。     

Angiotensin II desensitization and Ca2+ and Na+ fluxes in vascular smooth muscle cells

The role of ion fluxes in angiotensin II (AII) desensitization (tachyphylaxis) was investigated by studying Na⁺ and Ca²⁺ translocation in cultured vascular smooth muscle cells from the rat aorta. The effects of AII were compared to those of [1-sarcosine]-AII (Sar¹-AII), an analogue which also induces tachyphylaxis, and [2-lysine]-AII (Lys²-AII), an analogue that does not show this property. Maximally effective concentrations of the three peptides induced a rapid and transient increase in ⁴⁵Ca²⁺ efflux, a rapid and sustained decrease in total cell Ca²⁺ and an increased Na⁺ permeability. Repeated treatments, at short intervals, with either of the three peptides abolished the effect on Ca²⁺ efflux, and this desensitization was slowly reversible. A 30-min rest period was sufficient for full recovery of the response of cells that were desensitized by Lys²AII, whereas the recovery from AII or Sar¹AII-desensitization was still not complete after 60 min. Our results suggest that the difference in the behaviour of the tachyphylactic AII and Sar¹-AII and the non-tachyphylactic Lys²-AII lays not in the production of different signals upon binding to the receptor, but in a difference in the hormone-receptor interaction itself.     

Inhibition of angiotensin II and platelet-derived growth factor-induced vascular smooth muscle cell proliferation by calcium entry blockers

Summary Structural changes within the blood vessel wall such as hyperplasia and hypertrophy of vascular smooth muscle cells are important factors in the pathogenesis of hypertension. Humoral growth factors such as angiotensin II (AII) and platelet-derived growth factor BB (PDGF-BB) may participate in the remodelling of the blood vessel wall. Whether and by which mechanisms antihypertensive treatment is capable of influencing the structural blood vessel alterations to date remains unclear. In the present study, the effect of nifedipine and diltiazem on AII- and PDGF-BB-induced vascular smooth muscle cell proliferation was examined. Nifedipine and diltiazem at a concentration of 10 M did not affect baseline DNA synthesis in isolated vascular smooth muscle cells in culture. AII (final concentration 100 nM) and PDGF-BB (50 ng/ml) stimulated DNA synthesis by approximately 9.0- and 4.6-fold, respectively. Both AII- and PDGF-BB-induced DNA synthesis was significantly blunted by diltiazem and nifedipine in a concentration of 10 M, while no significant influence was seen with concentrations from 10 nM up to 1 M. In contrast, no significant influence of these drugs could be observed on fetal calf serum 5%-induced DNA synthesis. The findings indicate that calcium antagonists possess antimitogenic potential and that they may thus contribute to the regression of structural changes of the blood vessels associated with hypertension.Abbreviations PDGF-BB platelet-derived growth factor BB - AII angiotensin II - FCS fetal calf serum - VSMC vascular smooth muscle cells - ACE angiotensin I converting enzyme This work was supported by HEXAL-PHARMA, Holzkirchen, Federal Republic of Germany     

Isolation of vascular smooth muscle cells from a single murine aorta

The vascular smooth muscle cell plays a significant role in many important cardiovascular disorders, and smooth muscle biology is therefore important to cardiovascular research. The mouse is critical to basic cardiovascular research, largely because techniques for genetic manipulation are more fully developed in the mouse than in any othermammalian species. We describe here a technique for isolating smooth muscle cells from a single mouse aorta. This technique is particularly useful when material is limiting, as is frequently the case when genetically modified animals are being characterized.     

罗格列酮对胰岛素诱导的兔血管平滑肌细胞增殖的影响

目的：观察罗格列酮对胰岛素诱导的兔胸主动脉血管平滑肌细胞增殖的影响。方法:以组织块法原代培养兔胸主动脉血管平滑肌。采用细胞计数法测定细胞增殖，［3H］-TdR掺入法反映细胞DNA累积合成量。用RT-PCR方法测定蛋白激酶C mRNA含量。结果:罗格列酮对正常生长的细胞数目和掺入量无明显影响，与胰岛素组相比，1、5和10 μmol/L罗格列酮减少细胞数目分别为39.8%、46.9%和57.9%（P<0.01）；减少［3H］-TdR掺入量分别为29.6%、43.4%和53.8%（P<0.01）；对胰岛素诱导的a-PKC的表达上调无明显影响。结论:罗格列酮呈剂量依赖性抑制胰岛素诱导的平滑肌细胞的增殖。。     

An investigation of intrinsic buffering power in rat vascular smooth muscle cells

Intrinsic buffering power ( _i) has been measured in vascular strips and single cells from rat mesenteric artery. Intracellular pH (pH_i) regulation was inhibited to prevent overestimation of _i due to acid extrusion or entry via regulatory processes. At resting values of pH_i (7.0–7.2), a mean value of 41±4 mM/pH unit for _i was found. _i increased approximately fivefold from 30 to 150 mM/pH unit over the pH_i range 7.5–6.5. The mean data relating _i to pH_i could be described by relating _i to buffer concentrations and pK _a. This gave a value of 310 mM for buffer concentration and a pK _a of 6.0. As changes in pH_i are known to have marked effects on vascular tone then the increase in _i as pH_i falls may be considered as a means of attenuating pH_i decreases, before pH regulation restores pH_i to resting levels.     

胰岛素通过活性氧的产生促进VEGF表达及血管平滑肌细胞迁移和增殖

 目的:探讨活性氧（reactive oxygen species, ROS）在胰岛素促进的血管平滑肌细胞迁移和增殖中的作用及分子机制。方法:采用原代培养的大鼠主动脉血管平滑肌细胞,应用DCF-DA荧光探针检测细胞内ROS的生成;应用实时定量PCR、Western blotting和ELISA法检测mRNA和蛋白的表达;应用转染报告基因的方法检测基因的转录活性;划痕法测定细胞迁移;CCK-8法测定细胞增殖。结果:胰岛素处理后血管平滑肌细胞内ROS产生明显增加。过氧化氢酶和NADPH氧化酶抑制剂二亚苯基碘鎓（DPI）明显抑制胰岛素促进的ROS生成及p-Akt、p-p70S6K1和p-ERK1/2蛋白的表达。过氧化氢酶和DPI明显降低胰岛素促进的血管内皮生长因子（vascular endothelial growth factor, VEGF）的mRNA和蛋白表达及转录激活。抑制ROS产生明显抑制胰岛素刺激的血管平滑肌细胞迁移和增殖。结论: 胰岛素通过NADPH氧化酶途径促进血管平滑肌细胞ROS产生。ROS介导了胰岛素促进的Akt/p70S6K1和ERK信号通路的激活、VEGF表达及血管平滑肌细胞的迁移和增殖。     

血管紧张素II和洛沙坦对肝星状细胞合成胶原的影响

目的 :探讨血管紧张素II及其 1型受体 (AT1a)拮抗剂洛沙坦 (losartan) ,对肝星状细胞合成胶原的影响。方法 :①大鼠肝星状细胞的分离、培养及鉴定 ;②在不同浓度的血管紧张素II和洛沙坦作用下 ,采用 [3 H]-脯氨酸掺入释放法分别检测肝星状细胞生成胶原的情况。结果 :①细胞得率为 2× 10 7- 3× 10 7个 /只 ,活力在 95 %以上 ,纯度超过 90 %。②血管紧张素II在浓度为 10 -6mol/L - 10 -10 mol/L时 ,肝星状细胞生成胶原明显增多 (P <0 0 5 ) ;血管紧张素II浓度与胶原量呈正相关 (r=0 96 0 ,P <0 0 1)。洛沙坦在浓度为 10 -6mol/L - 10 -9mol/L时 ,胶原生成量显著减少 (P <0 0 5 ) ;且浓度与胶原生成量呈负相关 (r=- 0 882 ,P <0 0 1)。结论 :血管紧张素II可以促使肝星状细胞产生大量的胶原 ;洛沙坦通过拮抗AT1a后 ,胶原合成量显著减少 ,提示血管紧张素II在促使肝纤维化的发展过程中起着重要的作用 ,AT1a的拮抗剂有望为阻止肝纤维化发展提供新策略     

Effect of chronic nicotine delivery on the proliferation rate of endothelial and smooth muscle cells in experimentally induced vascular wall plaques

To study the effect of nicotine, cholesterol feeding, and their combination on endothelial and smooth muscle cells in vascular wall plaques an experimental method was established which allows the immunohistochemical detection and quantification of the fractions of endothelial and smooth muscle cells in DNA synthesis under the effect of these stimuli. For this purpose standardized fibromuscular plaques were produced by electrostimulation in the common carotid arteries of rabbits. The animals received either nicotine via implanted osmotic minipumps or a cholesterol diet or both. Plaque size was determined at the end of the experiments after 7 or 14 days as well as the fraction of endothelial and smooth muscle cells in DNA synthesis during exposure to bromodeoxyuridine (BrdU). The BrdU labeling index of endothelial cells clearly increased under chronic nicotine administration for either 7 days or 14 days compared to controls. The combination of nicotine and cholesterol diet led to a more significant increase. In contrast, the BrdU labeling index of smooth muscle cells was not increased under nicotine delivery. The combination of nicotine and cholesterol, however, led to a significant increase of the BrdU labeling index of smooth muscle cells in the plaques compared to cholesterol feeding. Measurement of the plaque size revealed no difference between controls and nicotine-treated animals after 14 days of nicotine delivery, whereas the combination of cholesterol and nicotine produced increased plaque formation compared to a group of animals which received a cholesterol diet alone.Abbreviations BrdU bromodeoxyuridine - EC endothelial cell - HDL high-density lipoprotein - LDL low-density lipoprotein - SMC smooth muscle cell     

Cyclosporine A enhances total cell calcium independent of Na-ATPase in vascular smooth muscle cells

The effect of cyclosporine A in enhancing vasconstrictor-induced calcium (Ca²⁺) mobilization in vascular smooth muscle cells may contribute to important side effects in cyclosporine therapy such as hypertension and nephrotoxicity. As we have previously shown, cyclosporine A stimulates transmembrane Ca²⁺ influx. Since Ca²⁺ efflux was not affected by cyclosporine A, we concluded that cyclosporine augments angiotensin II induced Ca²⁺ mobilization in vascular smooth muscle cells by an increased amount of Ca²⁺ in angiotensin II sensitive intracellular Ca²⁺ stores. The present study was therefore designed to examine the effect of cyclosporine A on cellular calcium content and on membrane calcium transport mechanisms. An important mechanism of Ca²⁺ extrusion from the cell is the Na-Ca exchanger. Its activity is closely related with that of the Na-ATPase. By increasing cellular sodium concentration the blockade of Na-ATPase would in turn activate cellular calcium uptake bx the Na-Ca exchanger. Therefore, we hypothesized that cyclosporine A might exert its effects in the same manner as a circulating Na-ATPase inhibitor. Total cell calcium was measured by atomic absorption and activity of Na-ATPase was estimated by an assay measuring phosphate production. Preincubation of the cells with cyclosporine (10 g/ml) for 15 min increased total cell calcium from 31.4 ± 5.0 to 46.5 ± 5.3 nmol/mg protein (P < 0.05). Activity of Na-ATPase was not affected by cyclosporine A (3.9 ± 0.2 vs. 4.3 ± 0.2 ol Pi h^–1 mg^–1 protein). Therefore, cyclosporine A induced Ca²⁺ influx is not mediated by an inhibition of the Na-ATPase. Cyclosporine-stimulated accumulation of cellular calcium may be mediated, for example, by opening of calcium channels in the plasma membrane. Increased Ca²⁺ mobilization in the presence of cyclosporine A may be due to an increased amount of Ca²⁺ avaible from intracellular Ca²⁺ stores. These results are of substantial significance for understanding the pathophysiological mechanisms of cyclosporine A induced vasoconstriction.Abbreviation CyA cyclosporine A Correspondence to: H. Meyer-Lehnert     

Migration of vascular smooth muscle cells is enhanced in cultures derived from spontaneously hypertensive rat

 Migration of vascular smooth muscle cells (SMC) constitutes a common step in neointimal formation which occurs in several vascular diseases. Whether the migratory response of SMC derived from hypertensive animals is different to that of controls may provide a clue to the link between hypertension and atherosclerosis. We examined the migratory responses of SMC from cell cultures and ring explants (thin aortic ring segment) and compared these responses between normotensive and hypertensive rats at two different ages. Both scrape-wound assay and transwell chambers from cultured aortic SMC as well as aortic ring explant cell outgrowth models were employed. The aortae were obtained from male spontaneously hypertensive rats (SHR) and their normotensive counterpart the Wistar-Kyoto rat (WKY) at 5 and 20 weeks of age. Migration was induced by fetal bovine serum or platelet-derived growth factor (PDGF) and migrated cells were counted at different times following stimulation. We found that SMC migration exhibited a high sensitivity to serum (range of ED₅₀: 2.2–3.6%), migration of SMC from 20-week-old SHR exceeded (by 46%, P<0.025) that of SMC from age-matched WKY and the difference became significant as early as 8 h after stimulation by serum. Chemotaxis induced by PDGF (2 h) exhibited similar differences. An elevated migratory response in SHR-SMC was also found in cells derived from 5-week-old rats in whom the blood pressure was normal. In younger animals, cell outgrowth from SHR aortic ring explants also accumulated more cells compared with WKY without a higher growth rate, thus suggesting that SHR-SMC have a higher migratory response ex vivo. In conclusion, aortic SMC migration appeared to be enhanced in various preparations from SHR. This difference also existed in young animals before the elevation of blood pressure occurred and might contribute partly to the role of hypertension as a risk factor for atherosclerosis. Received: 2 April 1997 / Received after revision: 2 September 1997 / Accepted: 8 September 1997     

A quantitative study of the relation between intracellular pH and force in rat mesenteric vascular smooth muscle

Strips of rat mesenteric artery were loaded with carboxy-seminaphthorhodafluor (SNARF) to measure intracellular pH (pH_i) and force simultaneously. pH_i was altered by using weak acids and bases. Alkalinization produced an increase in force. For equal elevations of pH_i a greater and faster increase of force was obtained in depolarized (high K⁺) than in non-depolarised preparations. Acidification produced little change in force unless the tissue was contracted (high-K⁺), in which case it elicited relaxation. Examination of the relationship between pH_i and force in depolarized preparations showed that acidification produced a greater change in force than alkalinization. Removal of weak bases produced a transient acidification that was accompanied by a fall in force in all preparations. This was followed by a secondary contraction in depolarized preparations during the period over which pH_i was acidic and being restored to resting values. Some preparations demonstrated a hysteresis in the relation between pH_i and force. It is concluded that the relationship between pH_i and force in mesenteric vascular smooth muscle is not constant but depends on the previous history of the preparation, and may involve differences in the interactions between H⁺, Ca²⁺ and the contractile machinery.     

大鼠细小动脉平滑肌细胞分离培养的新方法

目的：探讨大鼠细小动脉平滑肌细胞分离培养的新方法。方法：取大鼠肺分支动脉,先切成小块进行胶原酶的消化,约 ８ ｈ,而后用含２０％小牛血清的 ＤＥＭＥ培养基贴块培养。结果：培养 ２４ ｈ,可见有大量细胞游出贴瓶底生长,７２ｈ已融合成片,呈典型的“谷峰”样长势。尚有少量内皮细胞,通过消化传代除去。取传第三代细胞进行抗α－ａｃｔｉｎ免疫组织化学染色,大量饮泡,基膜下有密斑,密体。免疫组化鉴定培养细胞纯度为９６％。结论：应用消化贴块法培养的大鼠平滑肌细胞,方法简单,结果可靠,具有应用价值。     

大黄素对人血管平滑肌细胞增殖的影响

目的 观察大黄素对人血管平滑肌细胞周期时相和cyclin D1表达的影响,探讨大黄素抑制平滑肌细胞增殖的作用机制。方法 取对数增长期的平滑肌细胞同步于G0期,药物组:加入含37.5mg·L-1大黄素10％胎牛血清的培养液,对照组:仅加入10％胎牛血清的培养液;作用12、24、36、48 h后分别用流式细胞仪和Westemblot法进行细胞周期时相和cyclin D1表达的测定。结果 与对照组比较,药物组在各相同时间点C0/G1期细胞百分比升高,S期细胞百分比下降,且随着时间的延长差值增大,cyclin D1表达高峰延迟,表达量下调,细胞周期受阻于G0/G1期。结论 大黄素在抑制平滑肌细胞增殖的过程中通过下调,cyclin D1表达,从而阻滞细胞周期进程。     

血管紧张素转换酶抑制剂抑制血管平滑肌细胞增殖的机制

目的: 探讨血管紧张素转换酶抑制剂(ACEI)抑制动脉平滑肌细胞增殖及向内膜迁徙的机理。方法: 球囊导管损伤Wistar大鼠颈总动脉, 实验组于术前2 d开始给与ACEI(temocapril-HCl 10 mg·kg^-1·d^-1), 术后2 d、3 d、5 d分批处死。用抗人PDGF-A、-B及其受体, 抗人MMP-1、MMP-9等抗体以ABC法行免疫染色。动脉组织行放射自显影乳剂原位酶谱分析。电镜下观察细胞质内小器官及细胞周围弹性、胶原纤维的密度。结果: 给ACEI后, PDGF及其受体、MMP-1、-9蛋白阳性细胞率及明胶酶活性显著降低, 并抑制了中膜平滑肌细胞的表型转换。结论: ACEI可能通过继发地抑制PDGFs、MMPs蛋白表达, 阻碍细胞表型转换, 从而阻止中膜平滑肌细胞增殖及向内膜迁徙。     

血管紧张素Ⅱ对血管外膜成纤维细胞亚群转化的影响

目的:探讨血管紧张素Ⅱ(Ang Ⅱ)对大鼠胸主动脉血管外膜成纤维细胞亚群转化的影响。方法:采用克隆环法进行血管外膜成纤维细胞的单克隆培养,逆转录聚合酶链反应(RT-PCR)和免疫荧光染色方法鉴定细胞纯度;随机分为对照组和Ang Ⅱ(10~1 000 nmol/L)组,采用荧光定量聚合酶链式反应(FQ-PCR)、免疫荧光染色和Western blot法检测α-平滑肌肌动蛋白(α-SMA)的表达情况。结果:克隆环法获得血管外膜成纤维细胞2个亚群:圆形细胞亚群和纺锤形细胞亚群。自分型后,从第3代至第8代,纺锤形细胞亚群的α-SMA表达量有减少趋势,而圆形细胞亚群的α-SMA表达量显著增多。在Ang Ⅱ诱导下,纺锤形细胞亚群和圆形细胞亚群的α-SMA表达量均增多,且圆形细胞亚群随Ang Ⅱ浓度(10~1 000 nmol/L)的增加,α-SMA的表达量显著增多(P0.01)。Western blot实验结果显示,Ang Ⅱ能刺激圆形细胞亚群更多地转化为肌成纤维细胞。结论:Ang Ⅱ能不同程度地影响外膜成纤维细胞亚群的分化能力,进一步揭示出2个细胞亚群在血管重构过程中扮演不同角色。     

雌激素对大鼠血管平滑肌细胞囊泡素-1基因表达的影响

目的:探讨雌激素对血管平滑肌细胞囊泡素-1基因表达的影响。方法:取Wistar雌性大鼠,分为3组:假手术组,卵巢切除后皮下埋植雌激素组 (OVX+E组)及卵巢切除后皮下埋植安慰剂组(OVX+V组)。用药2周后处死大鼠,剥离主动脉平滑肌组织,提取总RNA进行半定量RT-PCR分析,检测雌激素对囊泡素-1(caveolin-1)基因表达的影响。为进一步明确雌激素是否直接调节血管平滑肌细胞caveolin-1基因表达,又采用100 nmol/L 17β-雌二醇(17β-E₂)处理培养的大鼠血管平滑肌细胞24 h,通过Northern blot分析检测雌激素对细胞caveolin-1 mRNA表达的影响。结果:OVX+E组大鼠主动脉平滑肌组织caveolin-1基因表达量明显高于OVX+V组,17β-E₂处理的培养细胞中caveolin-1基因mRNA表达量高于未用药的培养细胞。 结论:雌激素可促进血管平滑肌细胞caveolin-1基因表达,反映了雌激素心血管作用机理的一个方面。     

Circumferential alignment of vascular smooth muscle cells in a circular microfluidic channel

The circumferential alignment of human aortic smooth muscle cells (HASMCs) in an orthogonally micropatterned circular microfluidic channel is reported to form an in vivo-like smooth muscle cell layer. To construct a biomimetic smooth muscle cell layer which is aligned perpendicular to the axis of blood vessel, a half-circular polydimethylsiloxane (PDMS) microchannel is first fabricated by soft lithography using a convex PDMS mold. Then, the orthogonally microwrinkle patterns are generated inside the half-circular microchannel by a strain responsive wrinkling method. During the UV treatment on a PDMS substrate with uniaxial 40% stretch and a subsequent strain releasing step, the microwrinkle patterns perpendicular to the axial direction of the circular microchannel are generated, which can guide the circumferential alignment of HASMCs during cultivation. The analysis of orientation angle, shape index, and contractile protein marker expression indicates that the cultured HASMCs reveal the in vivo-like cell phenotype. Finally, a fully circular microchannel is produced by bonding two half-circular microchannels, and the HASMCs are cultured circumferentially inside the channels with high alignment and viability for 5 days. These results demonstrated the creation of an in vivo-like 3D smooth muscle cell layer in the circular microfluidic channel which can provide a bioassay platforms for in-depth study of HASMC biology and vascular function.