氟西汀对野百合碱诱导Wistar大鼠肺动脉和右心室构型重建的影响

目的 研究氟西汀对野百合碱(monocrotaline,MCT)诱导Wistar大鼠肺动脉和右心室构型重建的影响.方法 应用野百合碱建立大鼠肺动脉高压模型,40只Wistar大鼠均分为4组:对照组(control)、模型组(MCT)、氟西汀低剂量2mg/kg组(MCT+F2)和氟西汀高剂量lOmg/kg组(MCT+F1...     

Gax在肺动脉高压大鼠肺动脉中的表达变化

目的:使用低氧及野百合碱(monocrotaline,MCT)诱导的两种肺动脉高压(pulmonary arterialhypertension,PAH)大鼠模型,观察生长终止特异性同源盒(growth arrest-specific homeobox,Gax)在肺动脉的表达变化。方法:Sprague Dawley大鼠随机分为四组:低氧模型组(n=16)、低氧对照组(n=16)、MCT模型组(n=16)及MCT对照组(n=16)。采用插管法测定大鼠的右心室压力及肺动脉压力。右心室质量除以左心室和室间隔质量,计算右心肥厚指数。采用定量RT-PCR法测定肺动脉主干及肺组织Gax mRNA表达;采用Western免疫印迹法测定肺动脉主干Gax蛋白表达;免疫组织化学染色观测Gax在肺内的分布及表达变化。结果:低氧模型组及MCT模型组大鼠的右心压力、肺动脉压力及右心肥厚指数均显著高于相应对照组(P<0.01),两种模型大鼠的肺动脉血管均出现明显重构。与对照组比较,Gax mRNA在两种模型组大鼠的肺组织表达降低(P<0.05),而在肺动脉主干表达升高(P<0.05)。Gax蛋白在肺内主要表达在微小动脉。与对照组比较,两种模型组大鼠的肺动脉主干和肺微小动脉Gax蛋白表达均升高(P<0.05),而肺组织Gax蛋白表达下降(P<0.05)。结论:Gax主要表达在肺微小动脉,在PAH发生时表达上调。     

Oscillatory contractions in vertebral arteries from hypertensive subjects.

In response to several agonists, tail arteries from spontaneously hypertensive stroke prone rats (SHRSP) contract in an oscillatory manner not observed in tail arteries from normotensive rats. This study evaluated whether oscillations in force development characterize the contractile pattern of vertebral arteries from hypertensive humans. Vertebral arteries were isolated and studied within 18-24 h post mortem. Helical strips of the arteries were mounted in a muscle bath for isometric force recording. Contractile responses to serotonin (10(-7)M) and endothelin (10(-8)M) in arteries from hypertensive subjects were characterized by fluctuations in force development whereas those in arteries from normotensive subjects usually remained constant with time. The frequency of the response was approximately 1-2 contraction/relaxation cycles per min. This pattern of oscillatory contractile activity was observed in all but one of the hypertensive arteries (n = 15), and in approximately 40% of the normotensive arteries (n = 12). Oscillatory activity was converted to maintained contraction by nifedipine (10(-7)M) which also caused relaxation of the contractile response. Relaxation to acetylcholine (10(-6)M) and nitroglycerin (10(-6)M) did not alter the oscillatory contractions. Endothelium removal did not influence the oscillatory pattern of contraction. These observations suggest that oscillatory contractile activity in vertebral arteries from hypertensive subjects is related to abnormal calcium entry into the smooth muscle cells. This altered membrane property may contribute to changes in vascular reactivity in hypertension.     

Changes in main pulmonary artery of rats with monocrotaline-induced pulmonary hypertension

Hypertension is one of the most important risk factors for atherosclerosis, yet no morphologic evidence exists to explain it. This study is an attempt to identify lesions in the main pulmonary artery of rats in which pulmonary hypertension was induced by a single dose of monocrotaline. Pulmonary artery pressure was measured directly by catheterization or indirectly by measuring right ventricular thickness. Lesions were studied by both light and electron microscopy. As in previous studies in which monocrotaline was given chronically, we found thickening of the main pulmonary artery. We also found widening of subendothelial space, change in smooth-muscle cell polarity, shape, and organelle content (indicating change from contractile to secretory), focal areas of muscle necrosis and elastolysis. Interestingly, cardiac muscle was observed in adventitia of both controls and treated animals.     

Quercetin attenuates the progression of monocrotaline-induced pulmonary hypertension in rats

Pulmonary arterial hypertension (PAH) is a progressive disease associated with increased constriction and remodeling of the pulmonary vasculature.Quercetin is a natural flavonoid and has a variety of pharmacological effects including improvement of endothelial cell function.However,its pharmacological effects on pulmonary hypertension have been rarely reported.We sought to observe the protective effect of quercetin in rats with monocrotaline induced PAH.We divided 30 male Sprague-Dawley rats randomly into three groups with ten rats in each group:the monocrotaline group,the quercetin group and the control group.We found that,compared with the controls,the mean pulmonary artery pressure (mPAP) and the right ventricular hypertrophy index in the monocrotaline group were significantly higher (P < 0.01).Quercetin caused a significant reduction both in the mPAP and right ventricular hypertrophy index compared with the monocrotaline group (P < 0.01) while no difference was found between the quercetin group and the control group (P > 0.05).Monocrotaline induced a marked increase in the wall thickness (WT) in small and mid-sized pulmonary arteries compared with the controls (P < 0.01).Monocrotaline also induced a marked increase in the wall area (WA) in small [(56.38±6.65)% in monocrotaline vs.(19.80±4.63)% in control] and mid-sized [(43.71±5.38)% in monocrotaline vs.(14.24±3.66)% in control] pulmonary arteries (P < 0.01).Quercetin treatment markedly reduced monocrotaline induced increase in both WT and WA (P < 0.01),which,however,still remained significantly elevated compared with those of the controls (P < 0.01).Furthermore,compared with controls,proliferating cell nuclear antigen (PCNA) expression in the pulmonary artery tissues was markedly increased by monocrotaline [(45.59±1.27) in monocrotaline vs.(9.64±0.69) in controls],which was significantly attenuated by quercetin.Our animal experiment indicated that quercetin could have protective effects on monocrotaline-induced PAH.     

Endothelium-dependent relaxation in pulmonary arteries of L-NAME-treated Wistar and stroke-prone spontaneously hypertensive rats.

To evaluate whether the elevated blood pressure induced by chronic treatment with N(omega)-nitro-L-arginine methyl ester (L-NAME) contributes to an impairment of endothelium-dependent relaxation (EDR), the effects of chronic treatment of Wistar rats with L-NAME on systolic blood pressure, pulmonary arterial blood pressure and EDR of the pulmonary arteries were studied and compared with those of stroke-prone spontaneously hypertensive rats (SHRSP). While the systolic blood pressure (SBP) of Wistar rats was increased above that of controls by chronic treatment with L-NAME, it was still significantly lower than that of SHRSP. Chronic treatment with L-NAME did not affect pulmonary arterial blood pressure. On the other hand, the pulmonary arterial blood pressure of SHRSP was slightly but significantly higher than that of the control normotensive Wistar Kyoto rats (WKY). EDR in response to acetylcholine in the pulmonary artery of L-NAME-treated rats was significantly smaller than that in control Wistar rats. The EDR markedly increased in the presence of L-arginine and completely disappeared in the presence of N(omega)-nitro-L-arginine. Indomethacin hardly affected EDR. In preparations from SHRSP, the EDR was not different from that in those from WKY. Relaxation induced by sodium nitroprusside was identical in all preparations. Elevation of SBP and the impairment of EDR observed in L-NAME-treated rats recovered two weeks following cessation of treatment. These results suggest that the impaired EDR in the pulmonary artery of L-NAME-treated rats is not due to an L-NAME-induced increase in blood pressure but due to the inhibition of nitric oxide synthase by the drug remaining in the endothelium.     

过表达miRNA-29a对野百合碱诱导的大鼠肺动脉高压的作用

目的:检测微小RNA(miRNA)-29a在野百合碱诱导的肺动脉高压大鼠肺动脉血管壁组织中的表达,研究过表达miRNA-29a对肺动脉高压大鼠的影响,并探讨其初步机制。方法:在野百合碱诱导的肺动脉高压大鼠模型上,用实时荧光定量PCR测定肺组织miRNA-29a的表达水平;尾静脉注射miRNA-29a-mimic后,记录大鼠肺动脉压和体循环动脉压,苏木素-伊红染色观察肺动脉组织的形态,Western blot检测肺动脉组织中p-Akt与peNOS的蛋白水平。结果:野百合碱诱导的肺动脉高压大鼠肺动脉血管壁组织中miRNA-29a呈低表达;过表达miRNA-29a后,大鼠肺动脉压明显下降,体循环血压无显著变化,肺动脉中膜增厚程度显著减弱,肺血管重构现象不明显,p-Akt与p-eNOS的蛋白水平上调。结论:过表达miRNA-29a对野百合碱诱导的大鼠肺动脉高压具有改善作用,可能与激活PI3k/Akt-eNOS信号通路有关。     

端粒酶逆转录酶在野百合碱性大鼠肺动脉高压中的作用

目的:观察端粒酶逆转录酶(TERT)在野百合碱(MCT)性肺动脉高压(PH)大鼠模型中的肺组织中的表达变化。方法:用MCT复制大鼠慢性PH病理模型,用电磁血流量计观察肺血流动力学指标变化,用免疫组化法和图像分析技术测定肺组织中TERT的表达。结果:发现TERT可在大鼠肺血管平滑肌、支气管平滑肌和软骨组织中表达,并且MCT组肺组织中TERT表达较正常组呈明显阳性。结论:MCT性PH时TERT在肺血管平滑肌、支气管平滑肌的过度表达在MCT性PH的发病机制中可能具有重要意义。     

黄芩素对野百合碱诱导的肺动脉高压大鼠血管壁增厚的抑制作用

目的:观察黄芩素(baicalein)对野百合碱(monocrotaline,MCT)诱导的肺动脉高压(pulmonary artery hypertension,PAH)大鼠的治疗作用,并初步探讨其机制。方法 :28只雄性SD大鼠随机分为对照组、MCT模型组、黄芩素低剂量组和黄芩素高剂量组。除对照组外,其余各组大鼠皮下注射MCT建立大鼠PAH模型,黄芩素低、高剂量组于MCT注射2周后分别灌胃黄芩素50和100 mg·kg~(-1)·d~(-1),持续14 d,对照组灌胃等量生理盐水。造模4周后,测定大鼠右心室收缩压(right ventricular systolic pressure,RVSP)、右心室肥厚指数(right ventricular hypertrophy index,RVHI)和右心室质量指数(right ventricular mass index,RVMI);Masson染色检测肺组织纤维化程度;HE染色观察肺血管病理形态学变化;Western blot测定各组肺组织α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)蛋白水平及肺小动脉p38、ERK和JNK的磷酸化水平。结果:与对照组比较,MCT模型组大鼠的RVSP、RVHI和RVMI均明显升高(P0.01),肺组织纤维化明显,肺组织中α-SMA表达上调(P0.01),肺动脉壁增厚,肺小动脉p38,ERK和JNK磷酸化水平明显升高(P0.01);与MCT模型组相比,黄芩素高、低剂量组的RVSP、RVHI和RVMI明显降低(P0.01),肺组织纤维化和血管壁增厚明显改善,p38、ERK和JNK的磷酸化水平减少(P0.01)。结论:黄芩素可减轻MCT诱导的肺动脉高压,其作用通过抑制肺动脉壁增厚来实现,其分子机制可能与其抑制肺动脉的MAPK信号通路有关。     

Reversal of pulmonary vascular remodeling in pulmonary hypertensive rats

Pulmonary hypertension is responsible for significant mortality and morbidity among newborns and infants. The pathology is characterized by pulmonary vascular remodeling with medial hypertrophy and adventitial thickening, leading to decreased gas exchange. Since it is unknown if these abnormalities are reversible, we analyzed these vascular changes in pulmonary hypertensive rats. Exposure of rats to hypobaric hypoxia for 4 weeks induced clinical signs of pulmonary hypertension, such as increased right ventricular systolic pressure, increased right ventricular weight and considerable pulmonary vascular remodeling. The vascular changes were associated with the expression of Non -Muscle Myosin Heavy Chain B in the pre-acinar vessels and an increased expression of alpha Smooth Muscle Actin, Smooth Muscle Myosin Heavy Chain 2 and Calponin in the intra-acinar vessels. The right ventricular systolic pressure and right ventricular weight gradually decreased after specific periods of recovery in normoxia, although this reversal did not reach baseline levels after six weeks at normoxia. However, the cellular changes in the pulmonary vasculature were completely reversed. Development of pulmonary hypertension is associated with an increase of synthetic perivascular cells in the pre-acinar arteries and an aberrant differentiation of perivascular cells in the smallest intra-acinar arteries. These cellular and structural changes in the pulmonary vasculature are completely reversible after recovery in normoxia.     

Extracellular matrix protein gene expression in atherosclerotic hypertensive pulmonary arteries.

Lobar pulmonary arteries from patients with unexplained pulmonary hypertension were obtained at the time of single-lung transplantation to determine the response of large elastic vessels to increased intraluminal pressure. Specifically, human pulmonary arteries were examined to determine if remodeling remained active at the time of surgery and whether remodeling was similar to previously reported remodeling observed in several animal models. Grossly, the hypertensive vessels appeared atherosclerotic. Histochemical stains revealed a thick, diffuse neointima in hypertensive vessels compared with normal vessels. Immunohistochemistry demonstrated elastin protein in the neointima and in situ hybridization studies demonstrated tropoelastin mRNA largely in the neointima. Similarly, immunohistochemistry and in situ hybridization detected cellular fibronectin, thrombospondin and type I collagen protein and mRNA within the thickened intima from hypertensive vessels. These studies provide evidence that hypertensive vessels in patients with severe chronic pulmonary hypertension are actively remodeling but that the pattern of remodeling is different from previously described animal models.     

New findings in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension.

Rats have been kept in a hypobaric chamber, and thus hypoxic, for up to 28 days in order to study the structural changes in the pulmonary arteries during the development of pulmonary hypertension. Rats were studied after 3, 5, 7, 10, 14, 21 and 28 days at a pressure of 380 mmHg. Right ventricular hypertrophy was demonstrated after 5 days in the hypoxic environment but increased up to 10 days. After pulmonary arterial injection microscopic counts of small arteries showed that vessels up to 200 mum external diameter were gradually "lost", reducing the ratio of arterial to alveolar number significantly by 14 days. No vestiges of these vessels were found with light microscopy. At the same time a gradual increase in arterial wall thickness was demonstrated and also progressive extension of muscle into smaller and more peripheral vessels than normal. In both these features maximum increase was reached by 14 days of exposure though changes were apparent after only 3. Similar changes have been found in patients with cystic fibrosis and chronic bronchitis using the same measuring techniques.     

Hemin treatment abrogates monocrotaline-induced pulmonary hypertension

Treatment of rats with monocrotaline (MCT), a pyrrolizidine alkaloid plant toxin, is known to cause pulmonary hypertension (PH), and it has been used as a useful experimental model of PH. Recent findings suggested that pulmonary inflammation may play a significant role in the pathogenesis of MCT-induced PH. We also demonstrated that, following MCT administration to rats, there was a significant and sustained increase in the pulmonary expression of heme oxygenase-1 (HO-1), which is known to be induced by various oxidative stresses, including inflammation and free heme, and is thought to be essential in the protection against oxidative tissue injuries. In this study, we administered hemin (ferriprotoporphyrin chloride, 30 micromol/kg b.w., subcutaneously), a potent inducer of HO-1, every 3 days to rats following subcutaneous administration of MCT (60 mg/kg) and examined its effect on MCT-induced PH and pulmonary inflammation. MCT administration caused pulmonary arterial wall thickening with marked elevation of right ventricular pressure, in association with prominent pulmonary inflammation as revealed by the increase in gene expression of tumor necrosis factor-alpha and the number of infiltrated neutrophils in the lung. In contrast, hemin treatment of MCT-administered animals, which led to a further increase in pulmonary HO-1 mRNA expression, significantly ameliorated MCT-induced PH as well as tissue inflammation. These findings suggest that hemin treatment ameliorates MCT-induced PH possibly mediated through induction of pulmonary HO-1 which leads to the attenuation of pulmonary inflammation.     

氟西汀对BMPR2表达的影响以及对野百合碱诱导大鼠肺动脉高压的预防作用

目的探讨氟西汀对骨形态生成蛋白受体2(bone morphogenetic protein receptor 2,BMPR2)表达的影响以及对野百合碱(monocrotaline,MCT)诱导大鼠肺动脉高压(pulmonary arterial hypertension,PAH)的预防作用。方法将24只Wistar大鼠随机分成三组:对照组、MCT组和氟西汀处理组。采用多导生理记录仪测量血流动力学相关指标,HE染色方法观察肺动脉的形态学改变,以及利用RT-PCR方法检测肺动脉BMPR2的表达。结果与对照组相比,MCT组肺动脉压力、肺动脉中膜厚度百分比以及右心肥厚指数均明显升高,BMPR2在肺动脉上的表达明显减少(<0.01)。给予氟西汀处理后,氟西汀明显抑制了MCT诱发的肺动脉压力的升高、肺动脉重构和右心肥厚,并逆转了BMPR2的表达(<0.05)。结论肺动脉的构型重建可能与BMPR2的表达减少有关。氟西汀可能通过逆转BMPR2的表达有效地预防MCT诱导的PAH。     

Changes of gene expression after bone marrow cell transfusion in rats with monocrotaline-induced pulmonary hypertension

Pulmonary artery hypertension (PAH) causes right ventricular failure and possibly even death by a progressive increase in pulmonary vascular resistance. Bone marrow-derived mesenchymal stem cell therapy has provided an alternative treatment for ailments of various organs by promoting cell regeneration at the site of pathology. The purpose of this study was to investigate changes of pulmonary haemodynamics, pathology and expressions of various genes, including ET (endothelin)-1, ET receptor A (ERA), endothelial nitric oxide synthase (NOS) 3, matrix metalloproteinase (MMP) 2, tissue inhibitor of matrix metalloproteinase (TIMP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α in monocrotaline (MCT)-induced PAH rat models after bone marrow cell (BMC) transfusion. The rats were grouped as the control (C) group, monocrotaline (M) group, and BMC transfusion (B) group. M and B groups received subcutaneous (sc) injection of MCT (60 mg/kg). BMCs were transfused by intravenous injection at the tail 1 week after MCT injection in B group. Results showed that the average RV pressure significantly decreased in the B group compared with the M group. RV weight and the ratio of RH/LH+septum significantly decreased in the B group compared to the M group. Gene expressions of ET-1, ERA, NOS 3, MMP 2, TIMP, IL-6, and TNF-α significantly decreased in week 4 in the B group compared with the M group. In conclusion, BMC transfusion appears to improve survival rate, RVH, and mean RV pressure, and decreases gene expressions of ET-1, ERA, NOS 3, MMP 2, TIMP, IL-6, and TNF-α.     

Delayed intimal lesion development in cerebral arteries versus aortic and carotid arteries of spontaneously hypertensive rats

The development of intimal lesions is delayed in spontaneously hypertensive rats (SHR) in cerebral versus aortic and carotid arteries. The reason for this delayed involvement needs further study.     

Enhanced excitatory junction potentials in mesenteric arteries from spontaneously hypertensive rats

Excitatory junction potentials (EJPs) were examined using intracellular recording techniques in mesenteric arteries isolated from 12- to 15-week-old spontaneously hypertensive (SHR), Wistar Kyoto (WKY) and Sprague Dawley (SD) rats. The amplitudes of EJPs evoked by single supramaximal stimuli were larger in arteries from SHRs (12.9±0.7 mV,n=16) than in arteries from either WKYs (5.2±0.5 mV,n=24) or SDs (8.6±0.8 mV,n=15). The time constant of decay of EJPs did not differ significantly, suggesting that the passive electrical properties of the vascular smooth muscle are similar in the three rat strains. Spontaneous EJPs recorded in tissues from SHRs and WKYs had similar amplitude frequency distributions, suggesting that the quantal size is also similar between strains. In some arteries from SHRs, EJPs evoked by single stimuli triggered muscle action potentials (MAPs). Visible constriction only occurred following a MAP. In tissues from all three strains, summation of EJPs triggered MAPs. As EJPs are generated by the sympathetic co-transmitter adenosine 5-triphosphate (ATP), the findings of the present study indicate that purinergic transmission is enhanced in mesenteric arteries from SHRs, probably as a result of an increase in quantal release. A consequence is that when nerves are activated SHR arteries more readily undergo constriction that is dependent on voltage-activated Ca²⁺ influx.