自发性高血压大鼠心脏重构与ACE2 mRNA的表达

目的:观察不同月龄的自发性高血压大鼠(SHR)的心脏血管紧张素转换酶2(ACE2)mRNA表达水平,探讨心脏重构与ACE2的内在联系。方法:将12周龄雄性SHR 18只和12周龄WKY Wistar-Kyoto rats大鼠18只随机分为两组,从WKY大鼠组和SHR组中各抽取9只处死,剩余的9只再喂养12周后处死。测量大鼠心脏的质量(HW)与体质量(BW)并计算HW/BW的比值。以实时定量RT-PCR法检测ACE2 mRNA的表达。结果:①与同周龄WKY大鼠组比较,SHR组HW/BW的比值显著增加(P0.01);与12周龄SHR组比较,24周龄SHR组的HW/BW显著增加(P0.05)。②与同周龄的WKY大鼠组比较,SHR组ACE2 mRNA的表达显著降低(P0.01);与12周龄的SHR组比较,24周龄的SHR组ACE2 mRNA的表达显著降低(P0.01)。结论:自发性高血压大鼠心脏重构伴随着心脏中ACE2 mRNA的表达下调。     

夏膝颗粒对自发性高血压大鼠心肌TGF-β1表达的影响

目的 探讨夏膝颗粒对自发性高血压大鼠(SHR)心肌转化生长因子(TGF-β1)表达的影响及意义.方法 50只12周龄雄性SHR随机分为5组:SHR空白组、阳性药组、夏膝颗粒高、中、低剂量组各10只,分别予以缬沙坦和不同剂量的夏膝颗粒灌胃;同时选取8只同周龄的雄性Wistar-Kyoto大鼠(WKY)作为对照.给药8 w后采用RT-PCR法检测心肌TGF-β1 mRNA水平. 结果与WKY对照组比较,SHR空白组心肌TGF-β1/β-actin吸光值之比显著升高(P<0.01);与SHR空白组比较,夏膝颗粒高剂量组能显著降低SHR TGF-β1 mRNA的表达(P<0.01),甚至低于WKY组(P<0.05).结论 夏膝颗粒可能通过下调心肌TGF-β1的高表达,抑制心肌细胞外基质的增生,防止心室重构.     

可溶性细胞间黏附分子-1在自发性高血压大鼠肾损害作用的研究

目的研究可溶性细胞间黏附分子-1(intercellular adhesion molecule-1,ICAM-1)在自发性高血压大鼠(spontaneously hypertensive rat,SHR)肾脏的表达及其与肾损害的关系。方法以同龄雄性正常血压大鼠(WistarKyoto,WKY)和SHR为研究对象,分别于12周龄和24周龄时检测2种大鼠尾动脉血压、肾功能及β2微球蛋白(β2-MG),并采用免疫组织化学的方法检测ICAM-1在肾脏中的表达。结果同WKY组比较,SHR组24周时β2-MG显著增高(P<0.01),而且尾动脉收缩压(SBP)显著性增高;而尿素氮(BUN)和血肌酐(SCr)的差异无显著性(P>0.05)。ICAM-1在WKY组肾小管的表达无或极微量;在SHR组的肾小球有少量表达,但在肾小管的表达显著,且随高血压病程的进展,ICAM-1的表达显著性增加(P<0.01)。结论ICAM-1在SHR肾小管的表达显著增加,与肾损害的各项指标呈正相关。     

缬沙坦对自发性高血压大鼠肾脏的保护作用

目的探讨缬沙坦对自发性高血压大鼠(SHR)肾脏的保护作用,以及与结缔组织生长因子(CTGF)在SHR肾脏中表达的关系。方法本实验以12周龄雄性SHR和同龄雄性WistarKyotoRats(WKY)大鼠为研究对象,SHR分为治疗组[缬沙坦,30mg/(kg·d)、灌胃]与对照组,WKY大鼠为正常对照组,测量不同时期(12周,24周)大鼠尾动脉压、肾功能、尿β2微球蛋白(β2MG)的变化情况,以及用免疫组化的方法观察结缔组织生长因子在肾脏中的表达。结果12周后,相对于同龄WKY大鼠、SHR治疗组而言,SHR对照组的尿素氮、血肌酐变化无显著意义,而尾动脉压、尿β2MG均有显著增高(P<0.01,P<0.05)。经免疫组化半定量检测显示:在24周龄SHR对照组,其肾脏中CTGF的表达相对于同龄WKY大鼠及SHR治疗组明显升高(P<0.01),同时与尿β2MG的水平成正比(P<0.05)。结论缬沙坦能显著减少尿蛋白,同时使CTGF在SHR肾脏的表达明显减少,说明CTGF可能是慢性高血压导致的肾损害的重要机制之一。     

血管紧张素Ⅱ1a型受体在不同周龄自发性高血压大鼠血管组织中的表达及其甲基化状态的研究

目的通过对比观察不同周龄自发性高血压大鼠(SHR)和正常血压对照大鼠(WKY)胸主动脉和肠系膜动脉中血管紧张素Ⅱ1a型受体(AT1aR)的mRNA和蛋白质表达及其甲基化水平的差异,探讨DNA甲基化与AT1aR表达及血压状态的内在联系。方法以同龄WKY大鼠为正常对照,分别从转录和翻译水平检测处于高血压前期(4周龄)、高血压发展期(10周龄)和高血压稳定形成期(20周龄)SHR胸主动脉和肠系膜动脉内AT1aR的表达变化,同时应用重亚硫酸盐修饰测序法评估AT1aR基因启动子区的甲基化状况。结果 SHR和WKY大鼠胸主动脉和肠系膜动脉内AT1aR的mRNA和蛋白质表达水平均随周龄增长而递增;自10周龄起,SHR胸主动脉和肠系膜动脉内AT1aR的mRNA和蛋白质表达水平高于同周龄的WKY大鼠,20周龄时差异有统计学意义(mRNA:胸主动脉为1.607±0.084比1.227±0.079,肠系膜动脉为1.713±0.103比1.327±0.066;蛋白:胸主动脉为1.594±0.071比1.237±0.064,肠系膜动脉为2.103±0.115比1.300±0.089;均P0.01);SHR胸主动脉和肠系膜动脉内AT1aR基因启动子区两个CpG岛随着周龄的增长和血压的升高均发生去甲基化,自10周龄起SHR AT1aR基因启动子区甲基化水平已经开始低于同周龄的WKY大鼠,20周龄时差异有统计学意义(胸主动脉总甲基化率:1.4%比10.9%;肠系膜动脉总甲基化率:0.3%比8.0%;均P0.01)。结论 SHR动脉血管中AT1aR基因启动子区随着年龄的增加去甲基化,可能在影响AT1aR的表达和原发性高血压的发病机制中起到一定作用。     

贝那普利阻断RAS系统对自发性高血压大鼠心肌JAK-STAT信号通路的影响

目的探讨贝那普利对自发性高血压大鼠(SHR)心肌组织JAK-STAT信号转导通路及细胞凋亡的影响。方法30周龄WKY大鼠12只,同龄SHR24只,随机分为SHR组,贝那普利组10mg/(kg·d)。RT-PCR法检测AT1mRNA、AT2mRNA表达,免疫组化法检测心肌组织STAT1、STAT3表达及TUNEL末端标记法进行细胞凋亡检测。结果与SHR组比较,贝那普利组AT1mRNA表达水平显著降低(P<0.01),AT2mRNA表达水平显著增高(P<0.01)。与SHR组比较,贝那普利能降低STAT1表达(P<0.01),升高STAT3表达(P<0.01)。贝那普利组心肌细胞凋亡显著低于SHR组(P<0.01)。结论贝那普利能调节心肌组织JAK-STAT信号转导通路,抑制细胞凋亡,从而发挥其心脏保护作用。     

血管紧张素Ⅱ受体拮抗剂对高血压冠状动脉肥厚和功能异常的影响

目的 :研究血管紧张素 ( Ang )受体拮抗剂——氯沙坦对高血压冠状动脉肥厚和功能异常的影响。方法 :4周龄大鼠设 3组 :分别为自发性高血压大鼠 ( SHR)组、SHR口服氯沙坦组( SHR L)和正常血压大鼠 ( WKY)组 ,各 6只 ,饲养 12周。结果 :收缩压、冠状动脉横截面积、横截面积与内径比及中层血管平滑肌细胞宽度 :SHR L组较 SHR组显著下降 ( P<0 .0 5 ) ,与 WKY组无显著性差异 ;冠状动脉扩张储备力 :SHR L组较 SHR组显著增加 ( P <0 .0 5 ) ,且大于 WKY组。结论 :Ang 受体拮抗剂能预防 SHR冠状动脉肥厚和功能异常。     

厄贝沙坦对自发性高血压大鼠心肌Janus激酶-信号转导和转录活化因子信号通路的影响

目的 探讨厄贝沙坦对自发性高血压大鼠(SHR)心肌组织Janus激酶-信号转导蛋白和转录激活蛋白(JAK-STAT)信号转导通路及细胞凋亡的影响. 方法 30周龄WKY大鼠13只,设为WKY对照组;30周龄SHR 26只,随机分为SHR对照组和厄贝沙坦组.反转录-聚合酶链反应(RT-PCR)法检测血管紧张素Ⅱ1型(AT1)与2型(AT2)受体mRNA在心肌中的表达,免疫组化法检测心肌组织STAT1、STAT3表达,TUNEL细胞凋亡显色法进行细胞凋亡检测. 结果 (1)厄贝沙坦组与SHR对照组比较,AT1 mRNA表达水平显著降低(0.72±0.55对1.08±0.13,P<0.01),AT2 mRNA表达水平显著增高(0.30±0.32对0.25±0.35,P<0.01);(2)与SHR对照组比较,厄贝沙坦能降低STAT1表达(7.27±0.53对13.16±0.35,P<0.01),升高STAT3表达(5.41±0.37对4.82±0.34,P<0.01);(3)厄贝沙坦组心肌细胞凋亡率显著低于SHR对照组(P<0.01). 结论厄贝沙坦能调节心肌组织JAK-STAT信号转导通路,抑制细胞凋亡,从而发挥其心脏保护作用.     

氯沙坦对自发性高血压大鼠心脏血管紧张素转换酶2-血管紧张素(1～7)-MAS-ERK通路的影响

目的探讨氯沙坦对自发性高血压大鼠(SHR)心肌中血管紧张素转换酶2(ACE2)-血管紧张素(1～7)[Ang(1-7)]-MAS-ERK通路的影响。方法30周龄SHR随机分为SHR组(n=11)、氯沙坦组[氯沙坦灌胃30mg/(kg·d),n=12],以Wistar大鼠(WKY)作正常对照(n=12)。处理12周后,应用放射免疫法检测大鼠血浆及心肌组织血管紧张素Ⅱ(AngⅡ)、血管紧张素(1～7)[Ang-(1-7)]水平;采用RT-PCR法检测各组大鼠心肌血管紧张素转换酶(ACE)、ACE2和MAS受体mRNA水平;采用Western blot法检测ACE、ACE2和磷酸化细胞外信号调节激酶(pERK1/2)蛋白表达水平。结果用药12周后,氯沙坦组血压明显低于SHR组[(164.3±21.6)比(241.3±24.5)mmHg,P<0.01];SHR组心肌ACE mRNA和蛋白表达水平显著高于WKY组,而ACE2 mRNA和蛋白表达、心肌MAS受体mRNA表达水平明显低于WKY组,差异有统计学意义(P<0.01);氯沙坦组ACE2 mRNA和蛋白表达、MAS mRNA表达水平高于SHR组(P<0.01),心...     

高血压前期氯沙坦干预对成年自发性高血压大鼠阻力血管重塑及血管紧张素Ⅱ1型受体表达的影响

目的观察高血压前期氯沙坦干预对成年自发性高血压大鼠(SHR)阻力血管重塑和血管紧张素Ⅱ(AngⅡ)1型受体(AT_1R)表达的影响,探讨AT_1R表达、阻力血管重塑与早期干预引起的大鼠血压变化之间的内在关系。方法 4周龄的Wistar-kyoto(WKY)大鼠和SHR各16只,分别随机分为2组,共4组:WKY组、WKY氯沙坦干预组、SHR组、SHR氯沙坦干预组。干预组大鼠从4周龄开始给予氯沙坦30 mg/(kg·d)灌胃至10周龄,然后停药,尾套法监测收缩压。26周龄的大鼠分离肠系膜三级动脉,HE染色后观察血管结构,PowerLab生物信息采集系统记录血管舒张功能,实时荧光定量聚合酶链反应(PCR)及Western-blot检测血管中AT_1R mRNA和蛋白表达,酶联免疫吸附试验(ELISA)法检测血浆和肠系膜动脉中AngⅡ水平。结果 10周龄以后,SHR氯沙坦干预组的收缩压明显低于SHR组[26周:(208±12)比(226±11)mm Hg,P=0.018]。26周龄时,与SHR组相比,SHR氯沙坦干预组的肠系膜三级动脉的管壁厚度/管腔半径(0.17±0.03比0.29±0.08,P0.001)和管壁面积/管腔面积(0.33±0.08比0.47±0.10,P=0.001)较小,内皮依赖性血管舒张功能的最大舒张反应较强[(69.13±4.67)%比(43.87±3.31)%,P0.001],敏感性指标pD2较高(5.28±0.17比4.76±0.19,P=0.007),非内皮依赖性血管舒张反应的pD2也高(6.71±0.17比5.47±0.16,P0.001)。SHR氯沙坦干预组肠系膜动脉中AT_1R的a亚型mRNA(3.50±0.90比5.01±1.02,P0.001)及AT_1R蛋白表达(0.35±0.10比0.50±0.15,P=0.003)低于SHR组,而血浆和肠系膜动脉中AngⅡ水平高于SHR组(P0.05)。10周龄时,WKY氯沙坦干预组收缩压低于WKY组[(104±6)比(122±7)mm Hg,P=0.025]。但14周龄以后,WKY氯沙坦干预组与WKY组间的收缩压及上述血管指标的差异无统计学意义(P0.05)。结论高血压前期氯沙坦干预延缓成年SHR血压升高与阻力血管重塑改善、AT_1R表达下调有关。     

阿托伐他汀对自发性高血压大鼠心肌组织p21表达的影响及其意义

目的:观察阿托伐他汀(ATV)对自发性高血压大鼠(SHR)心肌组织中p21表达的影响,探讨其改善心肌肥厚的可能机制。方法:将16只8周龄SHR随机分为2组(n=8):ATV药物干预组(ATV组)与SHR模型对照组(SHR组),并以8只同周龄Wistar-Kyoto大鼠作为正常对照组(WKY组)。ATV组用ATV 50 mg/(kg·d)灌胃,SHR组与WKY组采用等容量蒸馏水每日同时灌胃。每隔2周测1次血压。10周后,观察大鼠血脂、心肌肥厚指标、p21 mRNA及其蛋白表达的改变。结果:干预10周后,ATV组及SHR组血脂、血压无明显差异。ATV组左室质量指数低于SHR组(P<0.01)。ATV组p21mRNA及蛋白的表达明显高于SHR组(P<0.01)。心肌组织p21mRNA的表达与全心质量与体质量比(HW/BW)呈负相关(r=-0.709,P<0.01),与左室质量与体质量比(LVW/BW)呈负相关(r=-0.665,P<0.01)。结论:ATV可上调SHR肥厚心肌组织中p21的表达,可有效改善左室肥厚。     

Increased expression of vascular endothelial growth factor and capillary density in hearts of spontaneously hypertensive rats

OBJECTIVE: The role of VEGF in vascular remodeling of target organs exposed to chronic hypertension is poorly understood. The authors compared capillary density (CD), capillary-to-fiber ratio (C/F), and VEGF mRNA expression in the hearts (left ventricle [LV]), and skeletal muscles (soleus and anterior tibialis [AT]) of 18-week-old male spontaneously hypertensive rats (SHR) and age-matched male Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats. METHODS: CD or C/F in LV, soleus, and AT of SHR, WKY, and SD rats was determined by analysis of randomly acquired digital images of cryosections stained with FITC-conjugated GS-I lectin. VEGF mRNA expressions in the tissues were determined by Northern blot. RESULTS: VEGF mRNA expressions in LV of SHR were 3.84- and 5.05-fold higher, compared to SD and WKY rats, respectively (n = 6; p < .01). There were no significant differences in VEGF mRNA expression in soleus or AT among SHR, WKY, and SD rats (p > .05). CD in LV of SHR (4975 +/- 167) was significantly higher than WKY or SD rats, 4151 +/- 169 and 3807 +/- 187 mm(-2), respectively (p < .05). In LV of SHR, C/F increased (35%) more significantly than CD (increased 20%), compared to WKY rats. CD, or C/F in soleus or AT of SHR was similar to that observed in WKY or 8D rats. CONCLUSIONS: VEGF expression, CD, and C/F in the heart (LV) of SHR are significantly increased, compared to WKY and SD rats. The data are consistent with the possibility that VEGF may contribute to capillary growth as a compensatory response to hypertension.     

Altered expression of BK channel beta1 subunit in vascular tissues from spontaneously hypertensive rats

Correlation of blood pressure (BP) with expression levels of large-conductance, voltage- and Ca2+-activated K+ (BK) channel beta1 subunit in vascular tissues from spontaneously hypertensive rats (SHR), Wistar-Kyoto rats (WKY), and Sprague-Dawley rats (SD) at different ages was investigated. Systolic BP and BK beta1 expression in mesenteric arteries at either mRNA or protein levels were not different among 4-week-old SHR, WKY, and SD. With hypertension developed at 7 weeks and reached plateau at 12 weeks, expression levels of BK beta1 mRNA in mesenteric arteries and aortae from SHR during this period of time were significantly higher than in age-matched normotensive WKY. The BK beta1 protein expression was significantly higher in mesenteric arteries from 12-week-old but not 7-week-old SHR when compared with age-matched WKY and SD. The BK beta1 protein levels in aortae were not different among 7-week-old SHR, WKY, and SD but were significantly lower in 12-week-old WKY than in age-matched SHR and SD. Captopril treatment normalized BP of 12-week-old SHR. This treatment downregulated BK beta1 protein in mesenteric arteries but upregulated it in aortae. No significant difference in BK alpha subunit expression was detected in mesenteric arteries from three strains of rats as well as the captopril-treated SHR. It appears that expression patterns of BK beta1 in vascular tissues vary depending on tissue types, animal age, and animal strains. Expression of BK beta1 in mesenteric arteries is closely correlated with BP in SHR. Increased BK beta1 expression in mesenteric arteries may represent a compensatory reaction to limit the development of hypertension.     

Altered angiotensin II-induced small artery contraction during the development of hypertension in spontaneously hypertensive rats.

This study assessed whether the angiotensin-II (Ang II)-induced contractile responsiveness of resistance arteries is altered during the development of hypertension in spontaneously hypertensive rats (SHR). Structural parameters and Ang II-stimulated contraction were determined in small mesenteric arteries from 6-week-old (phase of developing hypertension) and 21-week-old SHR (phase of established hypertension), compared with age-matched Wistar-Kyoto rats (WKY). To ascertain whether effects were specific for Ang II, contractile responses to another vasoactive agonist, vasopressin (AVP), were also determined. Systolic blood pressure was measured in conscious rats by the tail-cuff method. Segments of third-order mesenteric arteries (approximately 200 microm in diameter and 2 mm in length) were mounted in a pressurized system with the intraluminal pressure maintained at 45 mm Hg. Blood pressure was significantly increased in SHR (P < .001) and was higher in adult than in young SHR (P < .001). Ang II dose-dependently increased contraction, with responses significantly greater (P < .05) in SHR than in age-matched WKY. SHR, in the early phase of hypertension, exhibited significantly augmented contractile responses (Emax = 70 +/- 5%), compared with SHR with established hypertension (Emax = 33 +/- 5%). These effects were not generalized, as responses to AVP were not significantly different between young and adult SHR. Functional Ang II-elicited alterations were associated with structural modifications: 6-week-old SHR had smaller media to lumen ratio compared with 21-week-old SHR (8.1% +/- 0.17% v 10.6% +/- 0.20%, P < .01). In young SHR vessels the media cross-sectional area was unchanged relative to age-matched WKY rats, suggesting eutrophic remodeling (remodeling index 101.4% v 93.3% young v adult), whereas the cross-sectional area of adult vessels was increased in comparison to WKY rats, suggesting mild hypertrophic remodeling (growth index -1.0% v 15.2%, young v adult). In conclusion, the present study demonstrates that in SHR with early hypertension and slight medial thickening, Ang II-mediated vascular contractile responsiveness is significantly augmented compared with SHR with established hypertension and more severe vascular structural changes. These findings indicate attenuation, as hypertension progresses, of the initially enhanced vascular reactivity to Ang II that is present during the development of hypertension in SHR.     

Decreased Phorbol Ester-Induced Inhibition of Inositol Trisphosphate Formation Mediated by Alpha1-Adrenoceptors in Myocytes of Spontaneously Hypertensive Rats

Alpha₁-adrenoceptors, norepinephrine(NE)-stimulated formation of inositol trisphosphate (IP3) and inhibitory effect on this formation by 12-o-tetradecanoyl phorbol 13-acetate (TPA) were studied in isolated myocytes of 8-week-old spontaneously hypertensive rat (SHR) and Wistar-Kyoto rat (WKY). The number of alpha₁-adrenoceptors in myocytes of SHR was significantly increased than that of WKY. No significant difference in maximum response or EC50 values of NE-stimulated IP3 formation was observed between the two strains. Both norepinephrine-stimulated and GTPyS-stimulated IP3 formation was inhibited by TPA. The inhibitory effect was less in SHR than in WKY. PA did not change the number and affinity of alphal-adrenoceptors. These results suggest that myocytes of SHR may have abnormality in G protein and/or phospholipase C and that activation of protein kinase C might inhibit IP3 formation less in SHR than in WKY, a step distal to alphal -adrenoceptors, probably at a step distal to alphal -adrenoceptors.     

Age-related decrease of calcitonin gene-related peptide-containing vasodilator innervation in the mesenteric resistance vessel of the spontaneously hypertensive rat

We previously demonstrated that the mesenteric resistance blood vessels have nonadrenergic, noncholinergic vasodilator innervation in which calcitonin gene-related peptide (CGRP) is a possible neurotransmitter. The role of CGRP-containing vasodilator nerves in hypertension was investigated in perfused mesenteric vascular beds isolated from spontaneously hypertensive rats (SHR). The adrenergic vasoconstrictor responses to perivascular nerve stimulation in both SHR (8-, 15-, and 30-week-old) and age-matched Wistar-Kyoto (WKY) rat preparations increased with aging, but the response was greater in SHR than in WKY rats at all ages. The preparation isolated from SHR and WKY rats was precontracted by continuous perfusion of Krebs' solution containing 7 x 10(-6) M methoxamine plus 5 x 10(-6) M guanethidine. In both SHR and WKY rats, perivascular nerve stimulation (1-8 Hz) produced frequency-dependent vasodilation, which was blocked by 1 x 10(-7) M tetrodotoxin, pretreatment with 5 x 10(-7) M capsaicin, and denervation by cold storage (4 degrees C for 72 hours). The vasodilation induced by perivascular nerve stimulation in SHR greatly decreased with age, whereas a slight decrease in the response with age was found in WKY rats. The neurogenic vasodilation in the young SHR preparation was similar in magnitude to the vasodilation in age-matched WKY rats, whereas the vasodilation in 15- and 30-week-old SHR was significantly smaller than that in age-matched WKY rats. In both SHR and WKY rats, perfusion of rat CGRP (1 x 10(-10) to 3 x 10(-8) M) produced marked vasodilation in a concentration-dependent manner. The CGRP-induced vasodilation in SHR increased with age, whereas an age-related decrease in vasodilation was found in WKY rats. Perivascular nerve stimulation (4 and 8 Hz) of the perfused mesenteric vascular bed evoked an increased release of CGRP-like immunoreactive substance in the perfusate, which was significantly less in 15-week-old SHR than in age-matched WKY rats. Immunohistochemical studies showed an age-related decrease in CGRP-like immunoreactive fibers in SHR but not in WKY rats. These results suggest that CGRP-containing vasodilator innervation is greatly decreased when SHR develop and maintain hypertension. It is also suggested that the decreased vasodilator mechanism by CGRP-containing nerves contributes to the development and maintenance of hypertension.