白杨素对高血压大鼠的降压作用及机制研究

摘要 目的：探讨白杨素对高血压大鼠的降压作用及作用机制。方法：8只WKY大鼠为对照组,40只SHR大鼠随机分为模型组、卡托普利组和白杨素高、中、低剂量组,分别给予相应剂量药物治疗,每日1次,干预4周。实验期间观察各组大鼠收缩压（SBP）和舒张压（DBP）改善情况,酶联免疫吸附法（ELISA ）检测大鼠动脉血清中一氧化氮合酶（eNOS）、一氧化氮（NO）、内皮素（ET-1）和血管紧张素Ⅱ（AngⅡ）水平,马松染色（Masson）和苏木精-伊红染色法 ( HE) 观察大鼠心肌组织病理变化。结果：治疗后,与模型组相比,对照组、卡托普利组和白杨素高、中、低剂量组SBP和DBP均明显下降,血清eNOS和NO显著上升,ET-1和AngⅡ明显下降,差异具有统计学意义（P＜0.05）,其中白杨素高剂量组改善情况优于白杨素低、中剂量组（P＜0.05）;心肌细胞相关病理损伤减轻,白杨素高剂量组改善情况优于白杨素中、低剂量组。结论：白杨素可能通过调节血管舒缩因子和肾素-血管紧张素-醛固酮系统降低血压,并改善心肌组织病理损伤。     

基因多态性与原发性高血压的相关性

高血压是一种遗传因素和环境因素相互作用所致的疾病,但高血压的病因尚不明确。已有的研究结果表明,高血压患者或潜在患者常有一种以上与血压调节相关的基因异常。目前,已有多个与高血压相关的基因位点被深入广泛研究。本文旨在就基因多态性与高血压相关性的研究进展进行综述。     

不同年龄自发性高血压大鼠心脏AT2R的表达与心肌纤维化

目的观察不同年龄自发性高血压大鼠（SHR）心脏AT2R的表达水平及心肌胶原含量,探讨AT2R在高血压发生、发展过程中的作用。方法 1月龄组（S1）、2月龄组（S2）、3月龄组（S3）、6月龄组（S6）和9月龄组（S9）雄性SHR共五组,每组各6只,各组均有相应月龄的Wistar-Kyoto大鼠（WKY）作对照。采用RBP-I型大鼠血压心率测定仪测量大鼠动脉收缩压（SBP）;放免法（RIA）测定血浆血管紧张素Ⅱ（AngⅡ）;免疫组化染色结合计算机图像分析方法测定心脏AT2R的表达水平,天狼星红胶原染色大鼠的心脏切片。结果 1.SHR SBP随着月龄的增加呈持续上升（P〈0.05）,SHR的SBP均高于相应配对的WKY组（P〈0.05）。2.一个月后SHR血浆AngⅡ浓度均高于S1（P〈0.05）,一个月后SHR血浆AngⅡ浓度均高于相应配对的WKY组（P〈0.05）。3.SHR心脏AT2R免疫染色阳性面积比随着月份的增加而降低,SHR心脏AT2R免疫染色阳性面积比均低于相应配对的WKY组（P﹤0.05）4.SHR心肌中的胶原含量随着月龄的增加而增加。结论 SHR心脏AT2R表达水平比WKY低,并随着年龄的增加而降低。SHR心肌中的胶原含量随着月龄的增加而增加,而WKY无类似趋势。     

不同年龄白发性高血压大鼠肾脏AT1R和AT2R的表达

目的本研究观察不同月龄自发性高血压大鼠（SHR）肾脏ALR和ALR表达,初步探讨AT1R和AT2R在高血压发生、发展过程中的可能作用。方法1月龄组（S1）、2月龄组（S2）、3月龄组（S3）、6月龄组（S6）和9月龄组（墨）雄性SHR共5组,每组各6只,各组均有相应月龄匹配的Wistar-Kyoto大鼠（WKY）作对照。采用RBP-I型大鼠血压心率测定仪测量大鼠尾动脉收缩压（SBP）;放免法测定血浆血管紧张素Ⅱ（AngⅡ）;免疫组化染色结合计算机图像分析方法测定肾脏AT1R和ALR表达水平。结果（1）SHR SBP随着月龄的增加而上升,S6后趋于稳定。（2）1个月后SHR血浆AngⅡ浓度均高于S1（P〈0.05）,而S2、S3、S6和S9之间无明显差别（P〉0.05）;1个月后SHR血浆AngⅡ浓度均高于相应配对的WKY组（P〈0.05）;而WKY各月龄组均无明显差别（P〉0.05）。（3）SHR肾脏AT1R随着月份的增加而增加（P〈0.05）,且高于相应配对的WKY组（P〈0.05）。SHR肾脏ABR随着月份的增加而降低,S6明显降低（P〈0.05）,S6和S9比较无明显差别（P〉0.05）;且均低于相应配对的WKY组（P〈0.05）。WKY各月龄组AT1R和AT2R无明显差别（P〉0.05）。结论SHR肾脏AT1R表达水平比WKY高,并随着年龄的增加而递增;AT2R表达水平比WKY低,并随着年龄的增加而降低。     

降血压乳酸菌发酵乳对原发性高血压大鼠的降压效果

目的对具有血管紧张素转化酶(ACE)抑制活性的乳酸菌DM9057发酵乳的抗胃肠道酶解能力及原发性高血压大鼠(SHR)体内降压效果进行研究。方法以10 ml/kg和2.5 ml/kg发酵乳一次性和连续灌胃原发性高血压大鼠。结果 DM9057发酵乳具有较好的抗胃肠道酶能力,并且2个剂量均具有较好的降血压效果,其中以10 ml/kg剂量效果最为显著,一次性和连续灌胃后,最大降压值为(17.97±3.82)、(25.46±5.06)mmHg。结论乳酸菌DM9057发酵乳具有较强的抗胃肠道能力,同时在原发性高血压大鼠体内能够发挥一定的降血压作用。     

雌激素在中枢肾素-血管紧张素系统功能异常诱导的高血压中的保护作用

雌激素主要由卵巢分泌,是一种类固醇激素。流行病学研究显示,绝经前女性的高血压发病率明显低于同龄男性。研究表明,雌激素可通过影响中枢肾素-血管紧张素系统(RAS)组分的功能发挥其在中枢血压调控中的保护作用。雌激素作用于雌激素受体可抑制RAS增压信号通路或/和激活其减压信号通路,衰减中枢核团内自主神经元兴奋性进而延缓外界刺激诱导的高血压的发生。本文通过对雌激素在中枢RAS活动增强诱导的高血压发生中心血管保护作用及作用机制等方面进行综述,为临床开展性别差异性的高血压防治提供新思路。     

有氧运动改善自发性高血压大鼠肾纤维化的作用*

目的: 研究有氧运动训练对自发性高血压大鼠(SHR)肾脏纤维化影响, 探讨有氧运动对高血压肾损害的保护作用。方法: 8周龄雄性SHR和同龄Wistar京都大鼠(WKY)随机分为4组(n=6):安静WKY对照组(WKY-S)、安静SHR对照组(SHR-S)、低强度运动组(SHR-L)和中强度运动组(SHR-M)。SHR-L组、SHR-M组分别以14 m/min(最大有氧速度的35%)、20 m/min(最大有氧速度的50%)在0°坡度的运动跑步机上跑步,共运动14周,每周5次,每次60 min,WKY-S和SHR-S组安静饲养。14周后,运动训练结束72 h后检测大鼠血压;之后取血和肾脏检测血清肌酐SCr和尿素氮BUN含量,苏木精与伊红(HE)染色观察肾组织形态,Masson染色观察肾组织胶原沉积情况,计算肾脏胶原容积分数(CVF),检测肾脏 AngⅡ、AT1R、TGF-β、α-SMA、CTGF蛋白表达。结果: 与WKY-S组相比,SHR-S组的血压和血清SCr、BUN含量、肾脏CVF水平和AngⅡ、AT1R、TGF-β、α-SMA、CTGF蛋白表达均明显升高(P＜0.05);与SHR-S组相比,SHR-L组和SHR-M组血压和血清SCr、BUN含量、肾脏CVF水平和AngⅡ、AT1R、TGF-β、α-SMA、CTGF蛋白表达均明显下降(P＜0.05)且SHR-M组下降趋势更明显(P＜0.05)。结论: 有氧运动可通过抑制肾脏AngⅡ-AT1R-TGF-β通路,改善自发性高血压大鼠的肾纤维化与肾功能。     

自发性高血压大鼠中枢血管紧张素Ⅱ的变化对中枢肾上腺素...

The content of norepinephrine (NE) and epinephrine (E) in the brain of spontaneously hypertensive rats has proved abnormal, but the cause remained unknown. It was shown in the recent work that NE content in pons, posterior hypothalamus, nucleus caudatus and E concentration in medulla oblongata, anterior and posterior hypothalamus of 12-week old stroke-prone spontaneously hypertensive rats (SHRSP) were much higher than those of age-matched Wister-Kyoto rats (WKY). SHRSP also showed higher levels of systolic blood pressure (SBP) and brain angiotensin II (A II) than WKY. Intracerebroventricular (icv) perfusion of angiotensin-converting enzyme inhibitor captopril (20 micrograms for each time and three times for each day for four weeks) inhibited the synthesis of brain A II and reduced SBP and NE, E contents in all examined brain areas in SHRSP and WKY. However, the effects of chronically perfused captopril on SBP and brain NE, E levels in SHRSP were much more significant than in WKY. The results indicate that the modulatory effects of central renin-angiotensin system (RAS) on central adrenergic and noradrenergic system might be overactivated in SHRSP, which might partially responsible for the abnormally high levels of NE, E in some of the brain areas of SHRSP.     

血管紧张素转换酶2对心脏作用的研究进展

血管紧张素转换酶2作为肾素—血管紧张素系统的新成员,对心脏功能及心脏节律发挥着重要的调节作用。缺乏ACE2会造成心功能的下降,原因可能是心肌慢性缺氧、血管紧张素Ⅱ水平的提高、血管紧张素(1-7)对心脏保护作用的缺失以及其他肽类底物的增加。但同时ACE2的过度表达又会引起心脏传导紊乱和致死性的心律失常。因此,ACE2精确的生理作用有待进一步明确,但调节ACE2的活性可能为心血管疾病的治疗提出了新的思路。本文主要介绍了ACE2的分布与特性,及其对心功能及心脏节律的影响。     

Increased mRNA expression of cardiac renin-angiotensin system and collagen synthesis in spontaneously hypertensive rats

Hypertensive cardiac hypertrophy is associated with the accumulation of collagen in the myocardial interstitium. Previous studies have demonstrated that this myocardial fibrosis accounts for impaired myocardial stiffness and ventricular dysfunction. Although cardiac fibroblasts are responsible for the synthesis of fibrillar collagen, the factors that regulate collagen synthesis in cardiac fibroblasts are not fully understood. We investigated the effects of angiotensin II on cardiac collagen synthesis in cardiac fibroblasts. Cardiac fibroblasts of 10 week old spontaneously hypertensive rats and age-matched Wistar-Kyoto rats were prepared and maintained in culture medium supplemented with 10% fetal calf serum. The expression of mRNA of the renin-angiotensin system (renin, angiotensinogen, angiotensin converting enzyme) was determined by using a ribonuclease protection assay. Basal collagen synthesis in cardiac fibroblasts from spontaneously hypertensive rats was 1.6 fold greater than that in the cell of Wistar-Kyoto rats. Angiotensin II stimulated collagen synthesis in cardiac fibroblasts in a dose-dependent manner. The responsiveness of collagen production to angiotensin II was significantly enhanced in cardiac fibroblasts from spontaneously hypertensive rats (100 nM angiotensin II resulted in 185 ± 18% increase above basal levels, 185 ± 18 versus 128 ± 19% in Wistar-Kyoto rats p < 0.01). This effect was receptor-specific, because it was blocked by the competitive inhibitor saralasin and MK 954. These results indicate that collagen production was enhanced in cardiac fibroblasts from spontaneously hypertensive rats, that angiotensin II had a stimulatory effect on collagen synthesis in cardiac fibroblasts, and that cardiac fibroblasts from spontaneously hypertensive rats were hyper-responsive to stimulation by angiotensin II.Level of angiotensin and renin mRNA expressed in ventricles, and angiotensinogen mRNA expressed in fibroblasts from SHR were higher than those from WKY.These findings suggest that the cardiac renin-angiotensin system may play an important role in collagen accumulation in hypertensive cardiac hypertrophy.     

自发性高血压大鼠多组织炎症状态

高血压是一种慢性血管性疾病,易累及肾、肝、心、脑等组织,引起脑卒中和心、肾损害等并发症.本研究对高血压时肾、肝、心、脑等组织的炎症状态进行了观察.实验采用自发性高血压大鼠(spontaneously hypertensive rat,SHR)和正常血压的Wistar-Kyoto(WKY)大鼠,用RT-PCR和Western blot法观察肾、肝、心、脑等组织炎症相关因子IL-1p、TNFα、ICAM-1、iNOS、C/EBPδ和PPARγ的基因表达;紫外分光光度法观察蛋白质羰基化水平和FRAP法检测组织总抗氧化能力.结果显示(1)SHR组织炎症相关因子表达较对照WKY增强,除IL-1βmRNA在肝和脑的增加不明显外,其余均有显著性差异(P＜0.05);(2)SHR和WKY大鼠肾、心、脑蛋白质羰基化水平(nmol/mg蛋白)分别为8.93±1.08和2.27±0.43、2.23±0.23和0.17±0.02、13.42±1.10和5.72±1.01,SHR明显增加(P＜0.05);而肝脏蛋白质羰基化水平无明显变化;(3)SHR肾、肝、心、脑总抗氧化能力水平显著低于WKY大鼠(P＜0.05).以上结果表明,SHR多个组织(肾、肝、心和脑)均存在炎症因子被诱导和氧化应激反应等明显的炎症状态,提示炎症可能在高血压及其并发症的病理改变中起重要作用.     

自发性高血压大鼠心肌和血管组织牛磺酸的转运障碍

在自发性高血压大鼠（SHR）的心肌和主动脉血管组织上观察牛磺酸（taurine)转运和牛磺酸转运体（taurine transporter,TAUT) mRNA 的改变,结果显示,与对照组WKY大鼠相比,SHR组血浆牛磺酸水平和牛磺酸释放量增加,而心肌和血管组织牛磺酸水平和TAUT mRNA含量均降低,牛磺酸最大转运速率（Vmax)分别低24％和35％（P＜0．05）,米氏常数（Km)值分别高16％和39％（P＜0．05）,这些结果提示,SHR的心肌和血管组织牛磺酸转运障碍可能与TAUT活性和亲和力降低及TAUT基因水平的下调有关。     

自发性高血压大鼠和Wistar-Kyoto大鼠心血管组织肾上腺髓质素和肾上腺髓质素原N-末端20肽的水平

本工作观察了自发性高血压大鼠 (SHRs)和Wistar kyoto (WKY)大鼠心肌和主动脉肾上腺髓质素 (a drenomedullin ,ADM)和肾上腺髓质素原N 末端 2 0肽 (proadrenomedullinNterminal 2 0peptide ,PAMP)的水平。以放射免疫分析方法测定血浆、心肌和主动脉ADM含量。用竞争性定量逆转录多聚酶链式反应 (RT PCR)方法测定心肌和主动脉ProADMmRNA含量。结果发现 ,SHRs心肌和主动脉ProADMmRNA水平分别比WKY大鼠高 66 7%和 73 % (均P <0 0 1)。SHRs血浆、心肌和主动脉ADM ir含量分别较WKY大鼠高 2 9%、76 7%和 79% (均P <0 0 1)。SHRs血浆、心肌和主动脉PAMP ir水平分别较WKY大鼠高 42 5 % (P <0 0 1)、47 2 % (P <0 0 1)和 2 7 3 % (P <0 0 5 )。另外 ,SHRs的ADM和PAMP的比值较WKY大鼠明显增高 (心肌和主动脉分别为 2 0± 0 2 5vs 1 64± 0 3和 2 2± 0 18vs 1 5 6± 0 2 8)。结果提示 ,SHRs心肌和主动脉ProADM基因表达上调 ,ADM和PAMP水平升高 ,但二者升高的比例不一致。SHRs的ADM和PAMP升高不一致的病理生理意义有待进一步研究     

替米沙坦及吡哆胺对自发性高血压大鼠脑组织氧化应激的影响

目的:探讨替米沙坦及吡哆胺对自发性高血压大鼠脑组织氧化应激的影响。方法:自发性高血压大鼠24只随机分为4组(n=6):高血压对照组(HC组);替米沙坦组(T组);吡哆胺组(P组);联合治疗组(TP组)。同龄WKY大鼠作为正常对照组(NC组)。药物干预16周,测定各组脑组织中丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性及烟酰胺腺嘌呤二核苷酸磷酸(NADPH)氧化酶p47phox mRNA表达。结果:与NC组比较,HC组脑组织中MDA含量明显升高、SOD活性明显减低(P<0.05);与HC组比较T组、P组、TP组MDA含量明显减低,SOD活性明显升高(P<0.05);与NC组比较HC组(NADPH)氧化酶p47phox mRNA表达显著上调(P<0.01);与HC组比较T组、TP组NADPH氧化酶p47phox mRNA表达明显下调(P<0.01);HC组与P组比较NADPH氧化酶p47phox mRNA表达无统计学差异(P>0.05)。结论:自发性高血压大鼠脑组织处于氧化应激状态,替米沙坦及吡哆胺可抑制自发性高血压大鼠脑组织的氧化应激水平,联合治疗并不优于替米沙坦单药治疗。     

Novel antihypertensive hexa- and heptapeptides with ACE-inhibiting properties: from the in vitro ACE assay to the spontaneously hypertensive rat

Bioactive ACE inhibiting peptides are gaining interest in hypertension treatment. We have designed and screened six synthetic heptapeptides (PACEI48 to PACEI53) based on two hexapeptide leads (PACEI32 and PACEI34) to improve ACE inhibitory properties and assess their antihypertensive effects. ACE activity was assayed in vitro and ex vivo. Selected peptides were administered to spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats. In vitro cytotoxicity was assessed with the MTT reduction test. The six heptapeptides at low micromolar concentration produced different degrees of in vitro inhibition of ACE activity using the synthetic substrate HHL or the natural substrate angiotensin I; and ex vivo inhibition of ACE-dependent, angiotensin I-induced vasoconstriction, but not angiotensin II-induced vasoconstriction. Oral administration of the hexapeptide PACEI32L, and the heptapeptides PACEI50L and PACEI52L, induced reductions in systolic blood pressure lasting up to 3 h in SHRs but not in WKY rats. Intravenous injection of PACEI32L and PACEI50L, but not PACEI52L, induced acute transient reductions in mean blood pressure of SHRs. d-Amino acid peptides showed five-fold less ACE inhibitory potency, no inhibitory effect on angiotensin I-induced vasoconstriction, and antihypertensive effect in SHRs after i.v. injection, but not after oral administration. The toxicity of peptides to reduce the viability of cultured cells was in the millimolar range. In conclusion, we have obtained novel rationally designed heptapeptides with improved ACE inhibitory properties when compared to lead hexapeptides. One selected hexapeptide and two heptapeptides show oral antihypertensive effects in SHRs and appear safe in cytotoxicity assays.     

Novel Angiotensin I-Converting Enzyme Inhibitory Peptides Found in a Thermolysin-Treated Elastin with Antihypertensive Activity

Angiotensin I-converting enzyme (ACE) inhibitory activity was generated from elastin and collagen by hydrolyzing with thermolysin. The IC₅₀ value of 531.6 µg/mL for ACE inhibition by the elastin hydrolysate was five times less than 2885.1 µg/mL by the collagen hydrolysate. We confirmed the antihypertensive activity of the elastin hydrolysate in vivo by feeding spontaneously hypertensive rats (male) on a diet containing 1% of the elastin hydrolysate for 9 weeks. About 4 week later, the systolic blood pressure of the rats in the elastin hydrolysate group had become significantly lower than that of the control group. We identified novel ACE inhibitory peptides, VGHyp, VVPG and VYPGG, in the elastin hydrolysate by using a protein sequencer and quadrupole linear ion trap (QIT)-LC/MS/MS. VYPGG had the highest IC₅₀ value of 244 µM against ACE and may have potential use as a functional food.     

Increased density of fluorescent adrenergic fibers around the middle cerebral arteries of stroke-prone spontaneously hypertensive rats

The distribution of fluorescent adrenergic nerve fibers in the proximal portion (horizontal segment, Hs) and the three distal portions (major branches) of the middle cerebral arteries (MCA) was examined in stroke-prone spontaneously hypertensive rats (SHRSP) aged 10, 30, 60, 90, and 180 days, by the glyoxylic acid method. The results were compared with those in agematched normotensive Wistar Kyoto (WKY) rats. While the distribution pattern of fluorescent nerve fibers in the proximal portion of WKY rats changed from a straight linear arrangement at 10 and 30 days of age to a network-like arrangement after 60 days, those from SHRSP showed a constant meshwork pattern throughout the entire examination period. In the distal portions of the MCA of both SHRSP and WKY rats at all ages examined, fluorescent nerve fibers formed a coarse network. The distribution densities of adrenergic nerve fibers in the proximal and distal portions of the MCA of SHRSP were significantly higher (P<0.01 and 0.05) than those of WKY rats at all ages examined, except in the proximal portion at 90 and 180 days of age. The difference in nerve fiber density between SHRSP and WKY rats reached a peak at 30 days of age in both proximal and distal portions, and then gradually decreased with age. The present study suggests that sympathetic hyperinnervation is an important factor in the development of hypertension, and is involved in its maintenance in SHRSP.     

Pilot and plant scaled production of ACE inhibitory hydrolysates from Acetes chinensis and its in vivo antihypertensive effect

The angiotensin-I-converting enzyme (ACE) inhibitory oligopeptide-enriched hydrolysates from Acetes chinensis by treatment with the protease from Bacillus sp. SM98011 were produced at pilot scale (100 L) and plant scale (1000 L). The pilot and plant scaled hydrolysate products almost had the same properties as that at laboratory scale. Spray-drying had little effect on the peptide composition and bioactivity of the hydrolysates. The plant scaled hydrolysates were used to study its blood pressure-depressing effect in vivo. It caused reduce of 18.3–38.6 mmHg of the blood pressure of spontaneously hypertensive rats in dose-dependent manner in the range of 100–1200 mg/kg/day. Histopathologic study showed that the pathologic changes of heart and brain in SHRs got obvious alleviation after treatment of the hydrolysates.