Simvastatin attenuates smooth muscle neointimal proliferation and pulmonary hypertension in rats

Hypertensive pulmonary vascular disease is characterized by abnormal proliferation of vascular endothelial and smooth muscle cells, leading to occlusion of pulmonary arterioles, pulmonary hypertension, right ventricular failure, and death. Compounds with antiproliferative effects on vascular endothelial and smooth muscle cells, such as 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, may prevent the development of experimental hypertensive pulmonary vascular disease. Pneumonectomized rats injected with monocrotaline at 7 days develop severe hypertensive pulmonary vascular disease with neointimal formation. Rats were randomized to receive either vehicle or treatment with the HMG-CoA reductase inhibitor simvastatin (2 mg/kg per day). By Day 35, rats that received vehicle had higher mean pulmonary arterial pressures (53 +/- 2 mm Hg) and right ventricular hypertrophy (right ventricle/[left ventricle plus septum] [RV/LV+S] = 0.78 +/- 0.09) than rats in Group PMS5-35 that received simvastatin from Day 5 to 35 (mean pulmonary arterial pressure = 27 +/- 3 mm Hg, RV/LV+S = 0.34 +/- 0.08; p < or = 0.001). Pulmonary vascular remodeling with neointimal formation consisting of vascular smooth muscle cells was more severe in vehicle-treated rats (vascular occlusion score, 1.98 +/- 0.02) than in Group PMS5-35 (vascular occlusion score, 0.59 +/- 0.46; p < 0.001). In addition, lung endothelial nitric oxide synthase gene expression was decreased in vehicle-treated animals but was restored toward normal levels in simvastatin-treated animals. Simvastatin attenuates monocrotaline-induced pulmonary vascular remodeling with neointimal formation, pulmonary arterial hypertension, and right ventricular hypertrophy in rats.     

Nitrendipine attenuates the pulmonary vascular remodeling and right ventricular hypertrophy caused by intermittent hypoxia in rats

We designed experiments to determine whether intermittent hypoxia would produce significant pathologic and physiologic changes in rats and whether pretreatment with a calcium channel blocker, nitrendipine, would reduce the pulmonary vascular remodeling and right ventricular hypertrophy caused by intermittent hypoxia. Intermittent exposure to hypobaric hypoxia (0.5 atmospheres) 10 h a day for 30 days increased the hematocrit (65 +/- 1 versus 42 +/- 1%, mean +/- SEM), right ventricular systolic pressure (33 +/- 1 versus 20 +/- 1 mmHg), and right ventricular weight adjusted for body weight (RV/BW) (126 +/- 6 versus 60 +/- 2 mg/100 g) in male Sprague-Dawley rats. Intermittent hypoxia also increased the percentage of small pulmonary vessels with muscle (76 +/- 3 versus 19 +/- 5%) and the thickness of the vessel wall as a percentage of the total vessel diameter (34 +/- 1 versus 22 +/- 1%). Nitrendipine (10 mg/kg) prevented the acute increase in right ventricular systolic pressure caused by hypoxia. Chronic treatment with nitrendipine (10 mg/kg given twice a day by gavage for 30 days) significantly reduced the increase in hematocrit (61 +/- 1 versus 65 +/- 1%), right ventricular systolic pressure (29 +/- 1 versus 33 +/- 1 mmHg), and RV/BW (108 +/- 4 versus 126 +/- 6 mg/100 g) caused by hypoxia. Chronic treatment with nitrendipine also reduced the percentage of small pulmonary vessels with muscle (38 +/- 8 versus 76 +/- 3%) and prevented the increase in vessel wall thickness (20 +/- 2 versus 34 +/- 1%). Thus, nitrendipine treatment significantly reduces the right ventricular hypertrophy and pulmonary vascular changes caused by intermittent hypoxia.     

Right ventricular failure in patients with preserved ejection fraction and diastolic dysfunction: an underrecognized clinical entity

It is well recognized that patients with severe left ventricular (LV) systolic dysfunction develop pulmonary venous hypertension or postcapillary pulmonary hypertension, which leads to an increase in pulmonary vascular resistance (PVR) and right ventricular (RV) systolic failure. It is often underrecognized, however, that patients with heart failure with preserved LV ejection fraction and diastolic dysfunction may also develop postcapillary pulmonary hypertension with elevated PVR leading to RV systolic failure. This form of biventricular failure is a result of diastolic failure on the left in patients with preserved LV ejection fraction and systolic failure on the right. At this time, there are no randomized trials or guidelines addressing the management of patients with diastolic heart failure with and without resultant RV failure. The authors review the pathophysiology, clinical presentation, and suggested treatment of this underrecognized clinical entity.     

Low-molecular-weight heparin inhibits hypoxic pulmonary hypertension and vascular remodeling in guinea pigs

RATIONALE: We have shown previously that antiproliferative unfractionated heparins block hypoxia-induced pulmonary arterial hypertension (PAH) and vascular remodeling, and hypothesized that low-molecular-weight heparins (LMWHs) would too. OBJECTIVES: To determine the potential role and mechanisms of dalteparin and enoxaparin (two LMWHs) in inhibiting hypoxic PAH and vascular remodeling. METHODS: Male Hartley guinea pigs were exposed for 10 days to normobaric 10% oxygen with dalteparin (5 mg/kg), enoxaparin (5 mg/kg), or with an equivalent volume of normal saline solution. Normoxic control animals (n = 5) received room air for 10 days. Bovine pulmonary artery smooth-muscle cells (PASMCs) were grown in 10% fetal bovine serum without heparin, with dalteparin (1 microg/mL) or with enoxaparin (1 microg/mL). MEASUREMENTS: Pulmonary arterial pressure (PAP), cardiac index, right ventricular heart weight divided by left ventricular plus septum weight (RV/LV+S), hematocrit, percentage of wall thickness of intraacinar vessels (%WT-IA), percentage of wall thickness of terminal bronchiole vessels (%WT-TA), and the percentage of thick-walled vessels (%Thick) were determined. In PASMCs, expression of p27 and cell growth were compared because in mice whole heparin depends on p27 for its antiproliferative action. MAIN RESULTS: In hypoxic animals, hematocrit, PAP, total pulmonary vascular resistance index, RV/LV+S, %WT-IA, %WT-TA, and %Thick all rose significantly vs normoxic control animals (p < 0.05); cardiac index was unchanged. Dalteparin but not enoxaparin significantly reduced PAP, total pulmonary vascular resistance index, and RV/LV + S (p < 0.05 vs hypoxia alone); inhibited PASMC growth; and upregulated p27 expression. Enoxaparin moderately reduced vascular remodeling, which did not translate into less pulmonary hypertension. CONCLUSIONS: Not all LMWHs are the same. Dalteparin was more effective than enoxaparin in inhibiting pulmonary hypertension and vascular remodeling in hypoxic guinea pigs.     

血管内皮生长因子和内皮素在低氧性肺血管重建中的作用

目的探讨血管内皮生长因子(VEGF)和内皮素(ET)-1在低氧性肺动脉高压(HPH)及其肺血管重建中的作用,并观察钾通道开放剂(pinacidil)对HPH的防治作用及对VEGF和ET-1的影响.方法Wister大鼠46只,随机分为3组,对照组15只,低氧组16只,治疗组15只.缺氧组和治疗组大鼠缺氧[氧浓度为(10.0±0.5)%]4周,每天缺氧8h,其中治疗组大鼠于每天缺氧前腹腔注射pinacidil3mg/kg.缺氧4周后测定各组大鼠血清VEGF和血浆ET-1水平、平均肺动脉压(mPAP)、右心室(RV)/[左心室(LV)+室间隔(S)]比值及肺小动脉病理及其形态计量学.结果(1)缺氧组大鼠血清VEGF[(118.73±55.40)ng/L]和血浆ET-1[(221.2±56.2)ng/L]水平明显高于对照组(P＜0.01);缺氧组较对照组mPAP升高,RV/(LV+S)比值增高,肺小动脉血管壁显著增厚,管腔明显狭窄.(2)治疗组大鼠血清VEGF[(78.20±16.45)ng/L]和血浆ET-1[(181.6±30.5)ng/L]水平明显低于缺氧组(P＜0.01);治疗组较缺氧组mPAP下降(P＜0.01),肺小动脉血管壁增厚、管腔狭窄等明显减轻,但治疗组上述各指标仍未完全恢复到对照组水平.结论VEGF和ET-1在HPH及其肺血管重建中发挥重要作用,钾通道开放剂对HPH及其肺血管重建具有一定的逆转作用.     

Bone marrow-derived cells contribute to pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension

STUDY OBJECTIVE: In these days, it was reported that bone marrow (BM) cells might take part in the remodeling of some systemic vascular diseases; however, it remains unknown whether the BM cells were involved in the vascular remodeling of pulmonary arteries and the progression of pulmonary hypertension (PH). The purpose of this study was to investigate whether BM-derived cells contribute to pulmonary vascular remodeling in hypoxia-induced PH. MATERIALS AND METHODS: To investigate the role of BM-derived cells, we transplanted the whole BM of enhanced green fluorescent protein (GFP)-transgenic mice to the lethally irradiated syngeneic mice (n = 30). After 8 weeks, chimera mice were exposed to consistent hypoxia using a hypoxic chamber (10% O(2)) for up to 4 or 8 weeks (10 mice per group). After hemodynamics and the ratio of right ventricular (RV) weight to left ventricle (LV) weight, RV/(LV + septum [S]), were measured, histologic and immunofluorescent staining were performed. RESULTS: BM-transplanted mice showed a high chimerism (mean [+/- SEM], 91 +/- 2.3%). RV systolic pressure and the RV/(LV + S) ratio increased significantly with time in PH mice, indicating RV hypertrophy. Marked vascular remodeling including medial hypertrophy and adventitial proliferation was observed in the pulmonary arteries of PH mice. Strikingly, a number of GFP(+) cells were observed at the pulmonary arterial wall, including the adventitia, in hypoxia-induced PH mice, while very few cells were observed in the control mice. Metaspectrometer measurements using confocal laser scanning microscopy confirmed that this green fluorescence was produced by GFP, suggesting that these GFP(+) cells were mobilized from the BM. Most of them expressed alpha-smooth muscle actin, a smooth muscle cell, or myofibroblast phenotype, and contributed to the pulmonary vascular remodeling. A semiquantitative polymerase chain reaction of the GFP gene revealed that the BM-derived GFP-positive cells in the PH group were observed more than eightfold as often compared with the control mice. CONCLUSION: The BM-derived cells mobilize to the hypertensive pulmonary arteries and contribute to the pulmonary vascular remodeling in hypoxia-induced PH mice.     

低压低氧对SD大鼠肺动脉压及肺组织骨桥蛋白表达的影响

目的观察不同时间低压低氧刺激下SD大鼠肺动脉压及肺组织骨桥蛋白(OPN)表达的变化,探讨OPN在肺动脉高压发病机制中的作用。方法将30只SD大鼠随机分成5组:对照组(海拔2 260 m)、低压低氧(低压氧舱模拟5 000 m海拔)1天组、7天组、14天组、21天组,每组动物均测定平均肺动脉压(m PAP)和右心室肥厚指数[RV/(LV+S)];并分别采用RT-PCR法检测各组大鼠肺组织中OPN m RNA的水平,Western blot技术检测各组大鼠肺组织中OPN蛋白表达水平。结果低压低氧1天、7天、14天、21天组动物m PAP均高于对照组(P0.05),1天、7天、14天组呈逐渐增高趋势、21天组m PAP下降,差异有显著性(P0.05);低压低氧7天组、14天组、21天组动物呈现随低氧时间延长RV/(LV+S)逐渐增高的趋势、均高于对照组和1天组(P0.05),但1天组、7天组和对照组间差异无显著性(P0.05);RT-PCR法和Western blot法结果显示低压低氧1天、7天、14天、21天组动物肺组织中OPNm RNA、OPN蛋白表达水平与对照组比较均增高(P0.05)。结论低压低氧刺激可使m PAP和RV/(LV+S)增高并促进大鼠肺组织OPN的表达增高,因此OPN可能参与高原性心脏病形成中肺动脉压的增高和右心室重塑。     

Melatonin attenuates hypoxic pulmonary hypertension by inhibiting the inflammation and the proliferation of pulmonary arterial smooth muscle cells

Hypoxia‐induced inflammation and excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) play important roles in the pathological process of hypoxic pulmonary hypertension (HPH). Melatonin possesses anti‐inflammatory and antiproliferative properties. However, the effect of melatonin on HPH remains unclear. In this study, adult Sprague–Dawley rats were exposed to intermittent chronic hypoxia for 4 wk to mimic a severe HPH condition. Hemodynamic and pulmonary pathomorphology data showed that chronic hypoxia significantly increased right ventricular systolic pressures (RVSP), weight of the right ventricle/left ventricle plus septum (RV/LV+S) ratio, and median width of pulmonary arterioles. Melatonin attenuated the elevation of RVSP, RV/LV+S, and mitigated the pulmonary vascular structure remodeling. Melatonin also suppressed the hypoxia‐induced high expression of proliferating cell nuclear antigen (PCNA), hypoxia‐inducible factor‐1α (HIF‐1α), and nuclear factor‐κB (NF‐κB). In vitro, melatonin concentration‐dependently inhibited the proliferation of PASMCs and the levels of phosphorylation of Akt and extracellular signal‐regulated kinases1/2 (ERK1/2) caused by hypoxia. These results suggested that melatonin might potentially prevent HPH via anti‐inflammatory and antiproliferative mechanisms.     

低氧诱导大鼠肺动脉中5-HT_(1B)受体的过度表达

目的:观察低氧对大鼠肺动脉中5-羟色胺1B(5-HT1B)受体表达的影响,初步探讨了5-HT1B受体在低氧性肺动脉高压形成中的变化。方法:40只健康雄性SD大鼠随机分为正常组、低氧3周组、低氧4周组和低氧6周组,每组10只。除正常组外,其余3组大鼠分别在低氧环境中饲养3周、4周和6周。测定各组大鼠的平均肺动脉压力(mPAP)、右心室收缩压(RVSP)和右心室肥厚度。应用免疫组化染色法检测大鼠肺动脉上5-HT1B的分布和表达;用Western blot法测定大鼠肺组织中5-HT1B受体蛋白的含量。结果:与正常组相比,低氧3周组大鼠的mPAP、RVSP和右心室肥厚度均显著升高(均P0.05),并且随着低氧时间的延长而持续升高(均P0.05)。免疫组化染色的结果显示,5-HT1B受体主要分布在正常大鼠肺动脉的内膜层,平滑肌肌层中仅有少量表达;与正常组相比,低氧3周组大鼠肺动脉平滑肌肌层中5-HT1B受体的表达显著增多(P0.05);随着低氧时间的延长,表达持续增多。Western blot的结果表明,大鼠肺组织中5-HT1B受体蛋白含量的变化与免疫组化染色法检测的结果相一致。结论:低氧可以诱导大鼠肺动脉中5-HT1B受体的过度表达,这可能是5-羟色胺系统参与低氧性肺动脉高压形成的机制之一。     

Right ventricular thickness as predictor of global myocardial performance in systemic sclerosis: A Doppler tissue imaging study

Background

Cardiopulmonary involvement in systemic sclerosis (SSc) is a poor prognostic factor, due to pulmonary hypertension and right ventricular dysfunction. We assessed the echocardiographic parameters of right ventricular (RV) function in SSc and correlated echocardiographic findings to clinical features of the disease.

Methods

Thirty patients with SSc (cases) and 30 healthy, age-matched subjects (controls) were studied. Echocardiography, including tissue Doppler imaging, was used to evaluate cardiac function.

Results

Pulmonary hypertension could be documented in only 5 cases by Doppler echo, using Bernoulli principle. RV diastolic function was significantly deranged in cases. RV systolic function and left ventricle (LV) diastolic function were also significantly deranged in the cases. RV thickness was increased in patients with SSc. There were no significant differences in the echocardiographic variables between diffuse and limited subtypes of SSc. Myocardial performance index (MPI) of both ventricles were increased in cases. We could demonstrate RV thickness as the single most important predictor of MPI of both ventricles with sensitivity of 82% and specificity of 72% for RV-MPI and 63% for LV-MPI. Diastolic function was not found to be affected by disease duration or Rodnan skin score.

Conclusion

Patients with SSc exhibit abnormal RV and LV diastolic functions as well as abnormal RV systolic function. RV wall thickness was found to be simple and the single best predictor of global myocardial performance. RV dysfunction may be a response to intermittent pulmonary arterial hypertension, lung parenchymal involvement, or secondary to LV diastolic dysfunction in SSc.Abbreviations: ACE-I, angiotensin converting enzyme inhibitor; DT, deceleration time; DTI, Doppler tissue imaging; E/A ratio, early diastolic/atrial component velocity ratio; ET, ejection time; FVC, forced vital capacity; Hct, hematocrit; HRCT, high-resolution computed tomography; IVCT/ICT, isovolumic contraction time; ILD, interstitial lung disease; IVRT/IRT, isovolumic relaxation time; LV, left ventricle/ventricular; LVEDD, left ventricular end diastolic dimension; LVEDV, left ventricular end diastolic volume; LVEF, left ventricular ejection fraction; LVESD, left ventricular end systolic dimension; LVESV, left ventricular end systolic volume; MPI, myocardial performance index; PAH, pulmonary arterial hypertension; PAP, pulmonary artery pressure; PASP, pulmonary artery systolic pressure; PAT, pulmonary acceleration time; RR, electrocardiographic R–R interval; RVEF, right ventricular ejection fraction; RV, right ventricle/ventricular; SSc, systemic sclerosis     

Smooth muscle protein 22alpha-mediated patchy deletion of Bmpr1a impairs cardiac contractility but protects against pulmonary vascular remodeling

Vascular expression of bone morphogenetic type IA receptor (Bmpr1a) is reduced in lungs of patients with pulmonary arterial hypertension, but the significance of this observation is poorly understood. To elucidate the role of Bmpr1a in the vascular pathology of pulmonary arterial hypertension and associated right ventricular (RV) dysfunction, we deleted Bmpr1a in vascular smooth muscle cells and in cardiac myocytes in mice using the SM22alpha;TRE-Cre/LoxP;R26R system. The LacZ distribution reflected patchy deletion of Bmpr1a in the lung vessels, aorta, and heart of SM22alpha;TRE-Cre;R26R;Bmpr1a(flox/+) and flox/flox mutants. This reduction in BMPR-IA expression was confirmed by Western immunoblot and immunohistochemistry in the flox/flox group. This did not affect pulmonary vasoreactivity to acute hypoxia (10% O2) or the increase in RV systolic pressure and RV hypertrophy following 3 weeks in chronic hypoxia. However, both SM22alpha;TRE-Cre;R26R;Bmpr1a(flox/+) and flox/flox mutant mice had fewer muscularized distal pulmonary arteries and attenuated loss of peripheral pulmonary arteries compared with age-matched control littermates in hypoxia. When Bmpr1a expression was reduced by short interference RNA in cultured pulmonary arterial smooth muscle cells, serum-induced proliferation was attenuated explaining decreased hypoxia-mediated muscularization of distal vessels. When Bmpr1a was reduced in cultured microvascular pericytes by short interference RNA, resistance to apoptosis was observed and this could account for protection against hypoxia-mediated vessel loss. The similar elevation in RV systolic pressure and RV hypertrophy, despite the attenuated remodeling with chronic hypoxia in the flox/flox mutants versus controls, was not a function of elevated left ventricular end diastolic pressure but was associated with increased periadventitial deposition of elastin and collagen, potentially influencing vascular stiffness.     

Utility of right ventricular tissue Doppler imaging: correlation with right heart catheterization

Objectives: The objective of this study was to correlate tissue Doppler imaging of the right ventricle (RV) with pulmonary hemodynamics in patients referred for right heart catheterization. Methods: Seventy subjects (mean age 54 ± 13; 35 males) prospectively underwent tissue Doppler imaging of the RV and right heart catheterization within 1 day of each other. Peak systolic velocity and strain were measured at the RV free wall and correlated with pulmonary hemodynamics. Results: RV myocardial velocity demonstrated no correlation with any hemodynamic variable. While RV strain demonstrated significant correlation with cardiac index (r =−0.61; P < 0.001), correlations with transpulmonary gradient (r = 0.26; P < 0.05) and pulmonary vascular resistance (r = 0.30; P < 0.05) were weaker. Subgroup analysis revealed that in patients with left ventricular systolic dysfunction (n = 31), RV strain showed no correlation with any hemodynamic variable. In patients with normal left ventricular systolic function (n = 39), correlations were significant between RV strain and mean pulmonary artery pressure (r = 0.59; P < 0.001), pulmonary vascular resistance (r = 0.60; P < 0.001), and cardiac index (r =−0.67; P < 0.001). Conclusions: RV myocardial strain correlates significantly with pulmonary hemodynamics in patients with pulmonary hypertension and normal left ventricular function. However, there is no correlation with RV performance in patients with left ventricular dysfunction.     

Impairment of hypoxic pulmonary artery remodeling by heparin in mice

Chronic hypoxia produces pulmonary artery hypertension and remodeling of pulmonary arteries with hypertrophy of smooth muscle in the media and extension of smooth muscle into more distal small precapillary arteries. The present study investigated the influence of heparin, an inhibitor of platelet-derived growth factor, and of the clotting cascade on this remodeling. Mice maintained in room air or 10% O2 for 26 days were treated with low-dose heparin at 75 units/kg or high dose heparin at 300 units/kg. Pulmonary hypertension and right ventricular hypertrophy developed in the hypoxic mice compared with the room air mice as evidenced by the greater (p less than 0.05) right ventricular systolic pressure (36 +/- 4 SEM versus 21 +/- 1 mmHg) and the increase (p less than 0.05) in right heart weight/left ventricular plus septal weight (35 +/- 1.6 SEM versus 25.2 +/- 1.3). Hypoxia also induced smooth muscle hypertrophy in small pulmonary arteries, with an increase (p less than 0.05) in the percent media thickness/vascular diameter from 5.7 +/- 1 SEM to 13.3 +/- 3 and an apparent decrease (p less than 0.05) in distal small pulmonary arteries from 4.4 +/- 0.2 SEM to 2.05 +/- 0.1 per 100 alveoli. High-dose heparin partially but significantly (p less than 0.05) prevented the pulmonary artery hypertension (right ventricular systolic pressure of 28 +/- 2 mmHg), the right ventricular hypertrophy (right ventricular weight/left ventricular plus septal weight of 30.1 +/- 1) and remodeling of distal small pulmonary arteries (media thickness/vascular diameter of 8.4 +/- 1%, small pulmonary artery/100 alveoli of 3.63 +/- 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)     

长期低氧暴露对健康青年男性心脏结构和功能的影响

目的 通过对长期低氧暴露下健康青年男性心脏彩超基础数据的分析比较,揭示低氧暴露下心脏结构和功能的变化特征,探索防治高原肺动脉高压及慢性高原性心脏病的临床意义。 方法 纳入37名健康青年男性,采用低氧暴露前后自身对照的方法,利用心脏彩超测量左心房内径（LAD）、右心房内径（RAD）、左心室内径（LVD）、主动脉内径（AOD）、室间隔厚度（VST）、左室后壁厚度（LVPWT）、肺动脉内径（PAD）、右室流出道内径（RVOT）、左室短轴缩短率（LVFS）、左心室射血分数（LVEF）、左室舒张早期充盈流速（LVEDFV）、左室舒张晚期充盈流速（LVLDFV）、左室舒张早期/晚期充盈流速比（E/A）和肺动脉收缩压(PASP),进行对比分析。 结果 低氧暴露后,HR显著升高（P<0.01）,LVEF、LVFS及E/A均显著降低(均P<0.01);低氧暴露对心脏结构和功能有显著影响,低氧暴露后LAD、LVD、AOD、VST、LVPWT均显著降低（均P<0.01）,RAD（P<0.05）、PAD、RVOT（P<0.01）均显著升高。低氧暴露后,56.8%的受试对象肺动脉收缩压明显增高。PAH-组在低氧暴露后LVEDFV及E/A显著降低(均P<0.01),LVLDFV显著升高(均P<0.01);而PAH+组在低氧暴露后LVEF、LVFS、LVEDFV及E/A显著降低(均P<0.01),在低氧暴露前,PAH+组受试对象LVFS和LVEF均显著高于PAH-组(均P<0.05);PAH+组△LVFS和△LVEF的变化幅度均高于PAH-组（均P<0.01）。 结论 长期高原低氧暴露可引起肺动脉压升高以及心脏结构和功能发生显著变化;低氧暴露前LVFS和LVEF基础水平较高者或更易成为PAH易感人群。     

Cyclin-dependent kinase inhibitor p27Kip1, but not p21WAF1/Cip1, is required for inhibition of hypoxia-induced pulmonary hypertension and remodeling by heparin in mice

Heparin has growth inhibitory effects on pulmonary artery smooth muscle cell (PASMC) in vitro and in vivo. However, the mechanism has not been fully defined. In this study, we investigated the role of cyclin-dependent kinase inhibitors, p21(WAF1/cip1) (p21) and p27Kip1 (p27), in the inhibitory effect of heparin on PASMC proliferation in vitro and on hypoxia-induced pulmonary hypertension in vivo using p21 and p27-null mice. In vitro, loss of the p27 gene negated the inhibitory effect of heparin on PASMC proliferation, but p21 was not critical for this inhibition. In vivo, heparin significantly inhibited the development of hypoxia-induced pulmonary hypertension and remodeling, as evidenced by decreased right ventricular systolic pressure, ratio of right ventricular weight to left ventricle plus septum weight, and percent wall thickness of pulmonary artery, in p21(+/+), p21(-/-), p27(+/+), and p27(+/-), but not in p27(-/-) mice. We also observed that hypoxia decreased p27 expression significantly in mouse lung, which was restored by heparin. Heparin inhibited Ki67 proliferative index in terminal bronchial vessel walls in p27(+/+) and p27(+/-), but not in p27(-/-) mice exposed to hypoxia. Therefore, we conclude that the cyclin-dependent kinase inhibitor p27, but not p21, is required for the inhibition of hypoxic pulmonary vascular remodeling by heparin.     

Dynamic aspects of regulatory lung peptides in chronic hypoxic pulmonary hypertension.

Male Sprague-Dawley rats were placed in hypobaric hypoxia for 17-21 d (FIO2 10%) to establish pulmonary hypertension (PH) and control rats were kept in normobaric room air. Right mean atrial and ventricular pressures (PRA, PRV) were recorded, left ventricular (LV) blood was collected, and lungs were perfused with heparinized saline. Hearts were removed to evaluate right ventricular (RV) hypertrophy (RV/(LV+septum)%). Peptides were quantitated with radioimmunoassay in lung tissue extracts and plasma. Wet lung weight, PRA, PRV, and RV/(LV+S)% were higher and body weight was lower in hypoxia rats, and lung morphometry revealed increased arterial medial thickness (MT/OD%) and elastification of arterioles and capillaries. Lung tissue CGRP, PYY, gamma 2-MSH, and SOM were higher in PH rats and ANP was unchanged. Blood AVP, CGRP, PYY, VIP, and SOM were reduced in PH rats and ANP was unchanged. Lung levels of PYY and SOM correlated significantly with the time in hypoxia and with all parameters examined and CGRP and gamma 2-MSH correlated with all but medial thickness. PYY had the highest correlation of the peptides with body weight, PRV, and RV/(LV+S)%, and SOM the highest with time in hypoxia, wet lung weight, PRA, MT/OD%, and elastification of arterioles and capillaries. Blood peptides correlated inversely with these parameters. ANP had the overall weakest correlations and CGRP, PYY, and SOM had the highest. SOM correlated the highest with arterial medial hypertrophy, PRV, RV hypertrophy, and elastification of peripheral capillaries. VIP correlated the highest of the blood peptides with body weight and wet lung weight. Statistically significant correlations do not necessarily imply causal relationships. The putative roles of these peptides in pulmonary function are discussed.     

Effect of intermittent normoxia on chronic hypoxic pulmonary hypertension, right ventricular hypertrophy, and polycythemia in rats

The effect of continuous and intermittent normoxia on chronic hypoxic pulmonary hypertension, right ventricular hypertrophy, and polycythemia was studied in rats. After 4 wk in a hypobaric chamber (380 mmHg), the mean right ventricular blood pressure (Prv) was 29.2 +/- 1.8 (SEM) mmHg (n = 10) compared with 11.1 +/- 1.1 mmHg in 10 untreated control animals. After recovery in room air (24 h/day) for 6 wk, the Prv was significantly reduced to 21.2 +/- 3.5 mmHg (n = 6). Recovery using intermittent normoxia (8 and 16 h/day) for 6 wk did not reduce Prv. In 10 control rats, the ratio of right to left ventricular weight (RV/(LV + S) was 28.8 +/- 1.1%. After 4 wk of chronic hypoxia the RV/(LV + S) was 48.5 +/- 2.4% (n = 10). Recovery using complete normoxia for 6 wk significantly reduced the RV/(LV + S) to 32.8 +/- 1.9% (n = 6). Intermittent normoxia (8 and 16 h/day) did not reduce RV/(LV + S). Chronic hypoxia (380 mmHg) for 4 wk elevated the hematocrit from 35 to 66%. The polycythemia was reversed by recovery using continuous normoxia for 6 wk. Intermittent normoxia (8 and 16 h/day) was ineffective.     

阻塞性睡眠呼吸暂停患者肺动脉僵硬度的评价及其与低氧的关系

目的:旨在研究阻塞性睡眠呼吸暂停患者(OSA)夜间间歇性缺氧程度对肺动脉僵硬度(PAS)和右心室功能的影响。方法:对可疑OSA的患者进行多导睡眠图(PSG)和经胸超声心动图检查(n=376)。按夜间最低脉搏血氧饱和度(SpO2)分为三组(对照组:Sp O2≥90%,轻中度低氧组:80%≤SpO2<90%,重度低氧组:SpO2<80%)。比较三组患者的PAS和右心室功能,并进一步分析其相关影响因素。结果:最终本研究对278例患者进行分析。重度低氧组PAS显著升高(P=0.003),与平均肺动脉压(mPAP)有良好的相关性(r=0.780,P<0.001),而mPAP在不同组间差异无统计学意义(P>0.05)。各组间右心室功能相关参数,差异无统计学意义(P>0.05)。单因素和多因素Logistic分析表明,只有夜间最低SpO2(OR=1.807,P=0.001)是PAS升高的相关因素。结论:在重度低氧血症的OSA患者中PAS增加,仅夜间最低SpO2是其相关因素。     

吡那地尔防治大鼠低氧性肺动脉高压肺血管重建的实验研究

目的研究钾通道开放剂吡那地尔对低氧性肺动脉高压（ＨＰＨ）及其肺血管重建的影响。方法Ｗｉｓｔｅｒ大鼠４６只,随机分为３组：对照组１５只;低氧组１６只;治疗组（低氧＋吡那地尔）１５只。低氧组及治疗组建立低氧性肺动脉高压动物模型,治疗组于每天缺氧前腹腔注射吡那地尔３ｍｇ／ｋｇ。 ４周后测定各组平均肺动脉压（ｍＰＡＰ）、右心室（ＲＶ）／左心室＋室间隔（ＬＶ＋ Ｓ）比值和肺小动脉病理及其形态计量学。结果（１）低氧组ｍＰＡＰ、ＲＶ／（ＬＶ＋Ｓ）分别为（２８．４ ± ２．８）ｍｍＨｇ和（０．３０±０．０３）,明显高于对照组（１６．２±１．８）ｍｍ Ｈｇ和（０．２２±０．０３）（Ｐ＜０．０１）,管壁厚度与血管外径比值（ＭＴ％）、管壁面积与血管总面积比值（ＭＡ％）分别为（２５．７±２．６）％和（７５．３±５．６）％,亦明显高于对照组（１８．５±２．９）％和（５９．９±６．６）％（Ｐ＜０．０１）,管腔面积与血管总面积比值（ＶＡ％）为（２４．３±５．６）％,明显低于对照组（４０．７±８．１）％（Ｐ＜０．０１）。提示慢性缺氧导致大鼠发生明显肺动脉高压及右心室肥厚和肺小动脉管壁增厚、管腔狭窄等肺血管重建等改变。（２）治疗组ｍＰＡＰ、ＲＶ／     

间歇性低压低氧预适应延缓大鼠低氧性肺动脉高压发展并改善肺动脉舒张

目的 观察间歇性低压低氧预适应对大鼠低氧性肺动脉高压（HPH）及肺动脉舒张功能的影响。方法 将24只雄性SD大鼠随机分为:对照组、HPH组、间歇性低压低氧预适应组,每组8只。对照组动物常规饲养10周;HPH组动物先在同一室内常规饲养6周,然后按低压低氧法建立HPH模型（给予持续低压低氧4周）;间歇性低压低氧预适应组动物先给予预适应实验:HPH 1周,再放置同一室内常规饲养1周,如此重复循环3个周期共6周,然后按低压低氧法建立HPH模型（方法同HPH组）。分组模型建立后,用右心导管法测定肺动脉平均压（mPAP）、右心室平均压（mRVP）;称重测量右心室/（左心室+室间隔）〔RV/(LV+S)〕、右心室/体质量（RV/BW）;HE染色高倍镜下观察肺小动脉显微结构改变;取大鼠左、右肺动脉干制备血管环,行离体血管灌流实验,观察不同浓度乙酰胆碱和硝普钠的舒张血管作用。结果 与对照组比,HPH组大鼠的mPAP、mRVP、RV/(LV+S)、RV/BW均显著增高（P<0.01）;病理切片显示低氧后大鼠肺动脉平滑肌和弹力纤维层增生,血管壁增厚,管腔狭窄、变形;且低氧后大鼠肺动脉血管环对乙酰胆碱的舒张作用显著降低（P<0.01）。与HPH组比,经间歇性低压低氧预适应处理的大鼠mPAP、mRVP、RV/(LV+S)、RV/BW均显著降低（P<0.05）;病理切片显示肺动脉平滑肌和弹力纤维层增生及血管壁增厚有所缓解;且肺动脉血管环对乙酰胆碱的舒张作用显著增强（P<0.05）。结论 间歇性低压低氧预适应可增强大鼠肺动脉对低压低氧环境的耐受能力,延缓肺动脉高压和右心重构的发展,并改善肺动脉内皮功能。