Single lung transplantation in rats with fatal pulmonary hypertension.

Effects of single lung transplantation on fatal pulmonary hypertension were evaluated in rats receiving a lethal dose of monocrotaline. Inbred rats treated with monocrotaline (80 mg/kg) received a left lung isograft at 4 weeks (n = 9) and at 6 weeks (n = 6), when moderate and severe pulmonary hypertension, respectively, had developed. Medicated (n = 12) and nonmedicated rats (n = 12) served as control animals. Each rat was tested weekly with treadmill for exercise tolerance and oxygen consumption during a 10-week period after medication and after they were killed. Medicated control rats lost exercise tolerance and highest oxygen consumption per unit time consistently to the range of resting value (or 45% of nonmedicated control rats), and all died from severe pulmonary vascular occlusive disease with right ventricular hypertrophy before 10 weeks (right ventricular/left ventricular weight ratio of 1.16). All rats receiving a left lung isograft at 4 weeks survived and regained highest oxygen consumption per unit time (87% of nonmedicated control rats), with the lung transplant receiving 65% (nonmedicated control rats, 39%) of cardiac output and milder right ventricular hypertrophy (right ventricular/left ventricular weight ratio of 0.46). Except for one, all rats that received a left lung isograft at 6 weeks tolerated single lung transplantation, but they died soon after reperfusion because of pulmonary edema in the graft that received 58% of cardiac output with right ventricular/left ventricular weight ratio of 0.79. Results of single lung transplantation in rats were dependent on severity of pulmonary hypertension. In rats with moderate pulmonary hypertension, single lung transplantation was successful in reversing exercise intolerance and right ventricular hypertrophy. Single lung transplantation was unsuccessful when pulmonary hypertension was severe in the rat model because increased flow toward the lung transplant resulted in graft pulmonary edema.     

Failure to show decrease in small pulmonary blood vessels in rats with experimental pulmonary hypertension.

We induced chronic pulmonary hypertension in one group of rats by exposing them to chronic hypobaric hypoxia (380 mm Hg for three weeks) and in another group by administering a single subcutaneous dose of monocrotaline (60 mg/kg body weight). Both groups of rats showed increase of the right ventricular mean systolic blood pressure and right ventricular hypertrophy. We measured the surface area of histological sections of the left or right lungs and counted all small blood vessels with an external diameter of less than 50 microns and with a definite elastic coat lying distal to respiratory bronchioles. In the 10 rats with chronic hypoxic pulmonary hypertension the mean total number of small pulmonary blood vessels was 428.8 +/- 96.9 (SD) compared with 337.8 +/- 91.9 in 10 untreated control rats. The number of small pulmonary blood vessels per mm2 of lung tissue was 4.0 +/- 1.3 in the chronically hypoxic rats compared with 3.8 +/- 1.2 in the controls. The mean total number of small pulmonary blood vessels in nine rats with monocrotaline-induced pulmonary hypertension was 396.8 +/- 61.7 compared with 384 +/- 55.4 in three control rats. The number of small pulmonary blood vessels per mm2 lung tissue was 3.3 +/- 0.6 in the rats treated with monocrotaline compared with 3.6 +/- 0.6 in the control group. We conclude that the number of small pulmonary blood vessels is not reduced in rats with pulmonary hypertension induced by chronic hypoxia or monocrotaline.     

盐酸戊乙奎醚对野百合碱致大鼠肺动脉高压的抑制作用

目的探讨盐酸戊乙奎醚是否能够减缓野百合碱导致的大鼠肺动脉高压及是否能够预防或缓解肺血管重构。方法 3~4周龄健康雄性SD大鼠30只,体重90~100g,随机均分为正常对照组(C组)、野百合碱肺高压组(M组)、盐酸戊乙奎醚组(P组),每组10只。M组和P组腹腔注射野百合碱60mg/kg建造大鼠肺动脉高压模型,C组腹腔注射等容量生理盐水。P组大鼠于建模前15min时腹腔注射盐酸戊乙奎醚2mg/kg,建模第2天腹腔注射盐酸戊乙奎醚1mg/kg,C组和M组在相应时点腹腔注射等容量生理盐水,连续使用3周。在建模后第21天,三组大鼠检测血流动力学(肺动脉压、右心室压);处死大鼠前采集静脉血以备血液生化检测:ELISA法检测一氧化氮(NO)含量、内皮素-1(ET-1)含量。处死大鼠后留取左肺组织行病理切片以观察肺组织病理形态学变化,取右肺组织于-80℃冻存以备后续检测。结果 M组和P组右心室SBP、平均肺动脉压、肺动脉SBP和肺动脉DBP明显高于C组(P0.05);P组右心室SBP、平均肺动脉压、肺动脉SBP和肺动脉DBP明显低于M组(P0.05)。M组肺小动脉明显增厚,肺小动脉管腔狭窄甚至闭塞,肺组织炎性细胞浸润非常明显。P组肺小动脉壁增厚减轻,肺组织炎性细胞浸润减轻。M组大鼠血清中NO含量明显低于,ET-1的含量明显高于C组(P0.05);P组大鼠血清中NO含量明显高于M组和C组(P0.05),ET-1含量明显高于C组,但明显低于M组(P0.05)。结论使用野百合碱成功建造了大鼠肺动脉高压模型,NO含量降低、ET-1含量增加可能与野百合碱致大鼠肺动脉高压的形成有关;盐酸戊乙奎醚减缓野百合碱致大鼠肺动脉高压模型的肺动脉压力的升高、改善肺小动脉壁增厚可能与增加NO含量、降低ET-1含量有关。     

The effects of single lung transplantation in rats with monocrotaline-induced pulmonary hypertension

Abstract Acute haemodynamic change after single lung transplantation for primary pulmonary hypertension was evaluated using a rat transplantation model. Inbred Fisher 344 rats were administered with 40 mg/kg monocrotaline in order to induce pulmonary hypertension. The rats whose mean pulmonary arterial pressure (PAP) was over 30.0 mmHg received a left lung isograft from a normal donor after right heart catheterization. In the control group, PAP increased after single lung transplantation. On the other hand, in the pulmonary hypertensive group, PAP was significantly decreased 60 min after the transplantation, but 3 and 6 h after the transplantation, the PAP significantly increased again. On the day after the operation, it again decreased significantly. Left-to-right lung blood flow ratio was significantly increased in rats with pulmonary hypertension compared to rats with normal pulmonary pressure on both the 1st and 3rd postoperative days. The oedema of the grafted lung was more severe in the pulmonary hypertensive group than in the control group in the acute phase. In conclusion, single lung transplantation for pulmonary hypertension shifted pulmonary blood perfusion to the grafted lung and this shift made pulmonary oedema of the grafts more severe in the acute phase. These oedematous changes, which were more pronounced in the grafts in the pulmonary hypertensive rats, might have contributed to the transient rise in PAP in those rats after single lung transplanation.     

Graft damage after a single lung transplantation for pulmonary hypertension in a rat model

The hemodynamic effect and degree of damage in grafts of single lung transplants for pulmonary hypertension were studied in rats with monocrotaline-induced pulmonary hypertension. Inbred male Lewis rats (weight 200–230 g) were divided into two groups. Group 1 (control group,n = 16) underwent isogenic left lung transplantation, while group 2 (n = 15) received an intravenous administration of monocrotaline (80 mg/kg i.v.) and underwent isogenic left single lung transplantation 3 weeks later. Hemodynamic evaluations were performed prior to transplantation, at 1h postoperatively, and on days 3 and 7 after transplantation. Mean pulmonary arterial pressure (mPAP) rapidly declined after transplantation in group 2, from 39.3 ± 8.7 mmHg to 18.5 ±3.0 mmHg 1h after transplantation, and remained stable on day 7 after tranaplantation. No significant difference in the mPAP between the two groups was observed after tranaplantation. The extravascular lung water volume (ELWV: dry/wet ratio) in the right lung of group 2 significantly increased on day 3 (0.86 ± 0.02) (P < 0.01), and subsequently decreased to control levels on day 7 (0.83 ± 0.02). There was no significant difference in the ELWV in the grafted lungs between the two groups (0.84 ± 0.03 vs 0.86 ± 0.04), but there was tendency toward an increase in ELWV in group 2 on days 3 and 7. These data thus demonstrated that a hemodynamic improvement was obtained by single lung transplantation; however the degree of graft damage was remarkable in the pulmonary hypertension group.     

Right ventricular dysfunction after cardiac transplantation: primarily related to status of donor heart

BACKGROUND: It is unclear whether right ventricular dysfunction after transplantation is due to donor brain death-related myocardial injury or recipient pulmonary hypertension. METHODS: A canine donor model of brain death and a monocrotaline pyrrole-induced chronic pulmonary hypertension recipient model were established, and used for 30 orthotopic bicaval cardiac transplantations divided into three groups: Controls (group A, normal donor/recipient), group B (brain-dead donors/normal recipient), and group C (normal donor/recipients with pulmonary hypertension). Right ventricular function was measured before transplant and brain death, 4 hours after brain death, and after transplant (1 hour off bypass) by load-independent means plotting stroke work versus end-diastolic volume during caval occlusion. Right ventricular total power and pulmonary vascular impedance were determined by Fourier analysis. RESULTS: In comparison to the control group right ventricular preload-recruitable stroke work and total power decreased significantly after brain death and transplant in group B (from 22.7 x 10(3) erg (+/-1.2) at baseline to 15.6 x 10(3) (+/-0.9) after brain death and to 11.3 x 10(3) (+/-0.9) after transplant). In group C there was a significant increase in pulmonary artery pressure, impedance, right ventricular preload-recruitable stroke work, total power after transplant. CONCLUSIONS: Normal donor hearts adapt acutely to the recipient's elevated pulmonary vascular resistance by increasing right ventricular power output and contractility. Brain death caused significant right ventricular dysfunction and power loss, which further deteriorated after graft preservation and transplantation. The effects of donor brain death on myocardial function contribute to right ventricular dysfunction after cardiac transplantation.     

Gene transfer of human prostacyclin synthase into the liver is effective for the treatment of pulmonary hypertension in rats

BACKGROUND: As one of the future strategies of advanced pulmonary hypertension, intrinsic prostacyclin drug delivery using gene therapy may be useful. We investigated whether transfer of the prostacyclin synthase gene into the liver could ameliorate monocrotaline-induced pulmonary hypertension in rats. METHODS: The human prostacyclin synthase gene was transfected into the liver of rats with monocrotaline-induced pulmonary hypertension. Hemodynamic indices, blood samples, lung tissues, and survival curves were evaluated between rats receiving the gene and control rats. RESULTS: High levels of prostacyclin synthase gene expression were found in the hepatocytes of the prostacyclin synthase group. The level of 6-keto-prostaglandin F(1alpha) was significantly higher in the prostacyclin synthase group (prostacyclin synthase, 35.4 +/- 4.4 ng/mL; control, 22.3 +/- 3.3 ng/mL; P =.0436). The right ventricular/femoral artery pressure ratio was significantly lower in the prostacyclin synthase group than in the control group (prostacyclin synthase, 0.60 +/- 0.039; control, 0.88 +/- 0.051; P =.0036). The endothelin-1 levels in the lung tissues were significantly lower in the prostacyclin synthase group than in the control group (prostacyclin synthase, 10.42 +/- 2.01 pg/mg protein; control, 19.94 +/- 2.82 pg/mg protein; P =.0176). The survival ratio was significantly higher in the prostacyclin synthase group than the control group (P =.0375). CONCLUSION: This drug delivery system using gene transfer can be considered as an alternative for continuous intravenous prostacyclin infusion for pulmonary hypertension.     

Lung angiotensin converting enzyme activity in rats with pulmonary hypertension.

We have studied serum and lung tissue angiotensin converting enzyme (ACE) activity in female Wistar rats with pulmonary hypertension induced by two different methods. Chronic pulmonary hypertension was produced in one group of 10 rats (CH) by confinement in a hypobaric chamber (380 mmHg) for three weeks, and in another group fo 10 rats (M) by a single subcutaneous injection of monocrotaline (60 mg/kg body weight). In these two groups of tests rats and in 20 untreated controls (C), we evaluated right ventricular mean systolic blood pressure (Prvs mmHg), right ventricular hypertrophy, and serum ACE (n mol/ml/min). In lung tissue homogenate, we measured the specific activity of ACE (n mol/mg protein/min), alkaline phosphatase (AP) (IU/mg protein) and lactic dehydrogenase (LDH) (IU/mg protein). The Prvs in groups, C, CH, and M was 25 +/- 7 SD, 41 +/- 7, and 51 +/- 5, respectively. The ratio of right ot left ventricular weight (RV/(LV + S)%) in groups, C, CH, and M was 29 +/- 4, 52 +/- 5, and 56 +/- 7, respectively. The lung tissue ACE in groups C, CH, and M was 85 +/- 11, 65 +/- 20, and 22 +/- 5, respectively. In groups CH, and M the Prvs and RV/(LV + S)% were significantly elevated above control values while lung ACE was significant decreased (p less than 0.05). There was a significant inverse relationship between lung ACE on one hand, and Prvs (r = - 0.73) and RV/(LV + S)% (r = - 0.71) on the other hand. Serum ACE and lung AP were unchanged. In group M there was a slight but significant reduction in lung LDH. Chronic pulmonary hypertension, irrespective of its method of production, is associated with decreased lung ACE. The reduction in lung ACE is inversely proportional to the severity of pulmonary hypertension and right ventricular hypertrophy.     

Angiotensin converting enzyme activity and evolution of pulmonary vascular disease in rats with monocrotaline pulmonary hypertension.

We have investigated the role of angiotensin converting enzyme (ACE) in the development of pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular disease in rats given a single subcutaneous injection of the pyrrolizidine alkaloid monocrotaline. Thirty-six young female Wistar rats were divided into a test group of 27 animals and a control group of nine animals. Each test rat was given a single subcutaneous injection of monocrotaline (60 mg/kg body weight). On the first, third, fifth, seventh, tenth, twelfth, fourteenth, seventeenth, and twenty-second days after the injection of monocrotaline the mean right ventricular systolic blood pressure was measured in one control and three test rats. The animals were then killed and we measured the specific activity of ACE in serum and lung homogenate. We also evaluated muscularisation of pulmonary arterioles, medial hypertrophy of muscular pulmonary arteries, and right ventricular hypertrophy. The sequence of changes was as follows: muscularisation of pulmonary arterioles and medial hypertrophy of muscular pulmonary arteries were apparent seven days after administration of monocrotaline; pulmonary hypertension and reduced lung ACE activity occurred after 10 days; right ventricular hypertrophy was detected after 12 days. Serum ACE activity was unchanged. It is concluded that the reduction in lung ACE activity is a result rather than a cause of the pulmonary hypertension. This reduction in lung ACE activity may be a protective mechanism designed to limit the elevation of the pulmonary arterial pressure.     

Right ventricle-sparing heart transplantation effective against iatrogenic pulmonary hypertension.

BACKGROUND: Right heart failure is the predominant cause of death following heart transplantation, occurring with disturbingly high frequency in patients with severe antecedent pulmonary hypertension. We have recently reported a novel technique of heart transplantation that spares the recipient right ventricle, excising only the recipient left ventricle. The resulting model has 2 right hearts and 1 left heart. The aim is to preserve the recipient's right ventricle, which is already conditioned to pulmonary hypertension. The hope is that, in this way, death due to right heart failure can be prevented in humans. Our prior report was a feasibility study in normal dogs. This study challenges this new technique by creating iatrogenic pulmonary hypertension in the recipient animals. METHODS: Iatrogenic pulmonary hypertension was created in 4 recipient canines by intravenous injection of the pulmonary toxin monocrotaline pyrrole (single bolus of 3.5 to 4.5 mg/kg intravenously [i.v.]). RESULTS: Within 6 weeks of monocrotaline administration, relative pulmonary hypertension occurred (mean pulmonary artery [PA] pressure 20 mm Hg vs 10 mm Hg for controls [p < 0.01]) (pulmonary vascular resistance [PVR] 4.2 vs 1.5 Wood units [P < 0.01]), and right ventricular (RV) hypertrophy developed (RV thickness 11 mm vs 2 mm [P < 0.04]). Histologic examination confirmed severe muscle infiltration and thickening of the media of the pulmonary arterioles. RV-sparing heart transplantation was performed successfully in all 4 animals with pulmonary hypertension. In all cases, the animals were weaned without difficulty from cardiopulmonary bypass, despite the ambient pulmonary hypertension, on low-dose epinephrine, maintaining systolic blood pressure of 104 mm Hg at right atrial pressure of 7 mm Hg. Both right hearts contracted well without dilation or strain. A single "control" traditional orthotopic transplant experiment in an animal with monocrotaline-induced pulmonary hypertension resulted in immediate death from right heart failure. CONCLUSIONS: Right ventricle-sparing heart transplantation ("one-and-one-half heart model") can handle pulmonary hypertension without difficulty. This evidence adds impetus for further pursuing of right ventricle-sparing heart transplantation to decrease the incidence of death from right heart failure in recipients with severe antecedent pulmonary hypertension.     

Gene transfer of a TIE2 receptor antagonist prevents pulmonary hypertension in rodents

OBJECTIVES: Overexpression of angiopoietin 1 in the lung has been associated with human pulmonary hypertension. We hypothesized that inhibiting angiopoietin 1 signaling in the lung by administration of a receptor antagonist would block the development of pulmonary hypertensive vasculopathy in rodent models. METHODS: We injected 2 and 4 x 10(10) genomic particles of adeno-associated virus containing an extracellular fragment of the TIE2 receptor (AAV-sTIE2) into the pulmonary artery of 60 rats by using adeno-associated virus-lacZ and carrier-injected rats as control animals. Pulmonary hypertension was then induced by each of the following methods: (1) monocrotaline (group 1); (2) angiopoietin 1 expression in pulmonary vascular smooth muscle by adeno-associated virus gene transfer (group 2); or (3) oxygen deprivation (group 3). Animals were sacrificed at serial time points. At each time point, pulmonary artery pressures were measured, and pulmonary angiography was performed. Lungs were harvested for pathologic-molecular analysis. RESULTS: Each rodent pulmonary hypertension model demonstrated a significant increase in pulmonary artery pressures compared with that seen in control animals (P < .01). Administration of AAV-sTIE2 prevented pulmonary hypertension in the monocrotaline and angiopoietin 1 groups (from 44.6 +/- 2.1 to 18.8 +/- 1.9 mm Hg in the monocrotaline group and from 31.2 +/- 3.7 to 18.2 +/- 1.8 mm Hg in the angiopoietin 1 group, P < .001) but did not affect pulmonary hypertension in the hypoxia group. Pathologic analysis of group 1 and 2 lungs treated with AAV-sTIE2 demonstrated absence of smooth muscle cell proliferation within arterioles. Pulmonary angiography confirmed a lack of small pulmonary vessel occlusion in group 1 and 2 animals treated with AAV-sTIE2. CONCLUSIONS: Molecular blocking of the interaction between angiopoietin 1 and its endothelial receptor, TIE2, in the lung prevents pulmonary hypertension in 2 animal models of the disease. These experiments suggest a new strategy for understanding pulmonary hypertension based on the molecular biology of the pulmonary vascular wall.     

Right and left ventricular performance after single and double lung transplantation. The Toronto Lung Transplant Group

Twelve single lung and nine double lung transplant recipients were studied before transplantation and at 3 months and 1 year after transplantation with serial right and left ventricular radionuclide angiograms. The resting right ventricular ejection fraction increased in the double lung recipients from 31% +/- 5% before transplantation to 43% +/- 11% at 3 months after transplantation (p less than 0.05) and then remained stable to 1 year. The single lung recipients also demonstrated a significant rise in ejection fraction from 25% +/- 11% before transplantation to 36% +/- 12% at 3 months after transplantation. Again, this remained stable to 1 year. The exercise right ventricular ejection fraction also showed a significant posttransplantation rise in the double lung recipients (p less than 0.005) that remained stable to 1 year. In the single lung recipients a trend was seen for a rise in the exercise right ventricular ejection fraction that did not reach statistical significance by 1 year after transplantation. Neither group had a significant change in rest or exercise left ventricular ejection fraction. The systemic blood pressure increased significantly by 1 year after transplantation in both groups. The heart rate increase with exercise at 3 months after transplantation was significantly greater in the single lung group (42 +/- 13 beats/min) than in the double lung group (14 +/- 13 beats/min) (p less than 0.005). These data indicate that a significant improvement in right ventricular function occurs after single and double lung transplantation.     

二氯乙酸盐对肺动脉高压大鼠肺组织KV1.5表达的影响

目的 探讨二氯乙酸盐对肺动脉高压大鼠肺组织Kv1.5表达的影响.方法 雄性SD大鼠32只,8周龄,体重200～250 g,采用随机数字表法,将大鼠随机分为4组(n=8):正常对照组(C组)、二氯乙酸盐对照组(D组)、肺动脉高压组(PAH组)和二氯乙酸盐治疗组(PD组).采用左肺切除术联合皮下注射野百合碱60mg/kg的方法制备肺动脉高压模型.PD组于皮下注射野百合碱后,给予二氯乙酸盐80mg/kg灌胃,1次/d,连续28 d,PAH组给予等量生理盐水;D组不制备模型,给予相同剂量二氯乙酸盐灌胃.于皮下注射野百合碱后28 d时测定肺动脉压(PAP),随后处死,取肺组织,计算肺小动脉中膜厚度百分比和右心室肥厚指数,采用Western blot法检测增殖细胞核抗原(PCNA)和Kv1.5蛋白的表达水平,采用RT-PCR法检测Kv1.5 mRNA的表达水平.结果 与C组比较,PAH组和PD组PAP、中膜厚度百分比及右心室肥厚指数升高,肺组织Kv1.5 mRNA及其蛋白表达下调,PCNA表达上调(P＜0.05),D组上述指标差异无统计学意义(P＞0.05);与PAH组比较,PD组PAP、中膜厚度百分比及右心室肥厚指数降低,肺组织Kv1.5mRNA及其蛋白表达上调,PCNA表达下调(P＜0.05).结论 二氯乙酸盐减轻大鼠肺动脉高压与上调肺组织Kv1.5表达,抑制肺血管重构有关.

Abstract：

Objective To investigate the effect of dichloroacetate on the expression of Kv1.5 in a rat model of pulmonary arterial hypertension (PAH) .Methods Thirty-two male SD rats weighing 200-250 g were randomly divided into 4 groups ( n = 8 each): normal control group (group C), dichloroacetate control group (group D),PAH group, and PAH + dichloroacetate group (group PD). PAH was induced by left lung resection combined with subcutaneous injection of monocrotaline 60 mg/kg in PAH and PD groups. In group PD, dichloroacetate 80 mg/kg was given through a gastric tube into stomach once a day for 28 consecutive days after monocrotaline injection,while the equal volume of normal saline was given instead of dichloroacetate in group PAH. Group D only received dichloroacetate 80 mg/kg through a gastric tube into stomach once a day for 28 consecutive days. Pulmonary arterial pressure (PAP) was measured at day 28 after monocrotaline injection. The rats were then sacrificed and lung tissues were removed to calculate the percentage of thickness of the tunica media of pulmonary artery and right venicular hypertrophy index and to determine the proliferating cell nuclear antigen (PCNA) and Kv1.5 protein expression (by Western blot) and Kv1.5 mRNA expression (by RT-PCR).Results Compared with group C, the PAP,percentage of thickness of the tunica media, right ventricular hypertrophy index were significantly increased, Kv1.5 mRNA and protein expression was down-regulated and PCNA expression was up-regulated in groups PAH and PD ( P ＜ 0.05). Compared with group PAH, the PAP, percentage of thickness of the tunica media, right ventricular hypertrophy index were significantly decreased, Kv1.5 mRNA and protein expression was up-regulated and PCNA expression was down-regulated in group PD (P ＜ 0.05). There was no significant difference in the indexes mentioned above between group C and group D ( P ＞ 0.05). Conclusion Dichloroacetat alleviates PAH through upregulating Kv1.5 expression in lung tissues and inhibiting pulmonary vascular remodeling in rats.     

银杏叶提取物对野百合碱所致肺动脉高压保护作用的实验研究

目的：探讨银杏叶提取物对野百合碱所致肺动脉高压（PAH）的早期保护作用。方法：30只雄性 SD大鼠随机分为3组：对照组、PAH 模型组和治疗组,每组10只。PAH 模型组和治疗组大鼠采用脊背部皮下注射1%野百合碱60 mg/kg的方法复制PAH 模型,注射后第2天开始每日予2 ml 0.9%氯化钠注射液（PAH 模型组）或60 mg/kg银杏叶提取物（治疗组）灌胃;对照组脊背部皮下注射等量溶剂,注射后第2天开始每日予2 ml 0.9%氯化钠注射液灌胃。第22天采用颈外静脉右心导管法测定平均肺动脉压（mPAP）、右心室收缩压（RVSP）,测定右心室、左心室、室间隔的重量,计算右心室肥厚指数（RVHI）;采用 HE染色观察肺细小动脉组织结构情况,并计算直径50~150μm的肺小动脉血管管壁厚度占血管厚度百分比（WA%）和血管管壁面积与血管面积比值（WV%）;采用免疫组化方法观察内皮型一氧化氮合成酶（eNOS）及内皮素-1（ET-1）在大鼠肺组织中的表达情况。结果：PAH 模型组、治疗组的 mPAP、RVSP、RVHI、WA%、WV%与对照组比较均明显升高（P〈0.05）,治疗组的 mPAP、RVSP、WA%、WV%较 PAH 模型组均降低（P〈0.05）,而治疗组与 PAH 模型组的RVHI差异无显著性。免疫组化结果显示,3组 eNOS表达,对照组〉治疗组〉PAH 模型组;3组 ET-1的表达, PAH 模型组〉治疗组〉对照组。结论：银杏叶提取物通过抑制 ET-1的合成、减轻内皮细胞损伤、维持 eNOS的表达,达到减缓PAH 进展的作用。     

不同数目骨髓间充质干细胞移植对大鼠肺动脉高压的作用及内皮素-1表达的影响

目的探讨不同数目骨髓间充质干细胞(mesenchymal stem cells,MSCs)移植对野百合碱(MCT)诱导大鼠肺动脉高压的治疗作用,以及对内皮素-1(endothelin-1,ET-1)表达的影响。方法成年雄性Wistar大鼠40只(体重180～250 g),按随机数字表法分为4组,每组10只。A组:大鼠腹腔注射MCT 60 mg/kg,经颈外静脉注入1×106MSCs;B组:大鼠腹腔注射MCT 60 mg/kg,经颈外静脉注入5×105MSCs;MCT组:大鼠腹腔注射MCT60 mg/kg和等量磷酸盐缓冲液(PBS);对照组:大鼠腹腔注入等量生理盐水和等量PBS。MSCs移植4周后测定右心室收缩压(RVSP),计算心室比,即右心室/(左心室+室间隔)[RV/(LV+VS)];观察肺组织形态学改变;检测肺组织ET-1基因表达和血清ET-1的含量。结果 MSCs移植4周后,A组RVSP和RV/(LV+VS)与MCT组比较明显降低[(35.8±4.2)mm Hg vs.(47.2±10.1)mm Hg,P<0.01;(0.357±0.032)vs.(0.452±0.056),P<0.01];而B组与MCT组比较差异无统计学意义(P>0.05)。A组肺小动脉中膜厚度较MCT组明显变薄[(19.7%±3.0%)vs.(26.8%±3.6%),P<0.01];而B组则差异无统计学意义。逆转录酶-聚合酶链反应(RTase-PCR)检测结果显示,MCT组肺组织ET-1 mRNA表达最强,A组肺组织ET-1 mRNA与MCT组比较明显减弱,B组表达与MCT组接近。A组血清ET-1含量与MCT组比较明显减少。结论 MSCs静脉移植对MCT诱导的肺动脉高压具有抑制作用,并能减少肺组织ET-1的mRNA表达及血清ET-1浓度。采用1×106MSCs移植具有较好的治疗作用。     

Production and reversibility of right ventricular hypertrophy and right heart failure in dogs.

Combined heart-lung transplantation has been used for end-stage primary pulmonary hypertension. Experience with single-lung transplantation for other conditions suggested that associated severe right ventricular dysfunction resulting from increased afterload would recover after placement of a satisfactory lung allograft. Early experience with the application of single-lung transplantation for pulmonary hypertension supports this contention. We devised a reversible canine model of chronic progressive pressure-overloaded right heart failure by pulmonary artery banding to study the echocardiographic, hemodynamic, and pathological reversibility of the failing right heart. Clinical right heart failure was defined as the development of ascites and pleural effusions. Right heart failure developed in 23 dogs 67 to 348 days after banding, and they were divided into two groups to determine its early and long-term effects. Group 1 dogs (n = 11) were either sacrificed immediately after the onset of right heart failure (n = 5) or unbanded (n = 6); group 2 dogs (n = 12) were maintained in right heart failure for 3 months and then either sacrificed (n = 6) or unbanded. Unbanded dogs in both groups were observed for 4 additional months before sacrifice. A control group of 6 normal dogs was sacrificed for pathological comparisons. After unbanding, the right ventricular systolic pressure fell from 97 +/- 17 mm Hg (group 1) and 88 +/- 31 mm Hg (group 2) to 44 +/- 11 mm Hg and 47 +/- 13 mm Hg, respectively. Despite this persistent gradient across the pulmonary artery, echocardiographic and hemodynamic measures of right ventricular function returned to normal, albeit more slowly in the group 2 dogs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Single lung transplantation for pulmonary hypertension. Technical aspects and immediate hemodynamic results.

Donor availability has limited the clinical applicability of heart-lung transplantation in patients with end-stage pulmonary hypertension. Satisfaction with single lung transplantation in other patient groups prompted its extension to patients with pulmonary hypertension. Nine patients with end-stage pulmonary hypertension underwent single lung transplantation. Important technical considerations included routine use of cardiopulmonary bypass, simultaneous closure of significant associated cardiac defects (n = 4), and use of remaining thoracic donor organs in multiple recipients (total thoracic transplants from eight donors = 21). Analysis of immediate postoperative hemodynamics suggests that early relief of pulmonary hypertension and improvement in right ventricular function can be expected. There was one postoperative death. Eight patients have been discharged and are alive and well at a mean follow-up period of 1 year. All eight survivors have returned to New York Heart Association functional class I from their preoperative levels of III or IV. These results support the use of single lung transplantation as a transplant option in patients with end-stage pulmonary hypertension. The question of long-term durability remains unanswered.     

大鼠野百合碱肺高压模型血小板衍生生长因子mRNA的表达及作用

目的 观察血小板衍生生长因子(PDGF)A、B及其α,β受体在大鼠野百合碱肺高压模型中的表达,探讨PDGF在肺血管重构中的作用.方法 SD大鼠24只,体质量250～300g,随机分为野百合碱注射组(MCT,12只)和对照组(Con,12只).MCT组给与野百合碱60 mg/kg单次皮下注射.喂养6周后,使用逆转录-聚合酶链反应(RT-PCR)观察肺组织PDGF-A、PDGF-B及其α、β受体mRNA转录量的变化.结果 MCT组肺组织中PDGF-A、PDGF-B、PDGFR-α、PDGFR-β的mRNA转录水平都高于对照组(1.5609±0.1246比0.4057±0.0007,P＜0.05;0.4810±0.0733比0.2639±0.0070,P＜0.05:0.4963±0.0137比0.3038±0.0859,P＜0.05;1.1257±0.2490比0.0736±0.0185,P＜0.05).结论 血小板衍生生长因子(PDGF)-A、PDGF-B及其α、β受体活性表达的增强,参与了肺动脉高压肺血管重构的机制.     

Hemodynamic unloading leads to regression of pulmonary vascular disease in rats

OBJECTIVE: Treatment options for patients with advanced pulmonary vascular disease caused by a congenital heart defect are still mainly limited to heart-lung transplantation or lung transplantation with repair of the cardiac lesion. Because we have previously shown that the structural changes associated with pulmonary hypertension can be reversed by stress unloading in an organ culture model, we now investigate whether hemodynamic unloading will lead to regression of pulmonary vascular disease in the intact animal. METHODS: Right middle and lower lobectomy and monocrotaline injection were performed in Lewis rats (n = 22) to cause pulmonary vascular disease from a combined hemodynamic and toxic injury. Twenty-eight days later the left lungs were examined (n = 10) or exposed to normal pulmonary artery pressure for an additional 14 (n = 5) or 28 (n = 7) days by transplantation into healthy recipients. Pulmonary artery pressure, ventricular weight, and pulmonary artery morphology were evaluated in each group. RESULTS: Pulmonary hypertension (50 vs 16 mm Hg; P <.001) and right ventricular hypertrophy (right ventricular/left ventricular weight 0.69 vs 0.32; P <.001) associated with pulmonary artery medial hypertrophy (28.2% vs 7.2% wall thickness; P <.001) and muscularization of small pulmonary arteries (92.3% vs 19.4%; P <.001) developed by day 28 (compared with untreated controls). However, transplantation into healthy recipients effectively unloaded the lungs (mean pulmonary artery pressure 17 and 24 mm Hg at 14 and 28 days after transplantation) and resulted in progressive normalization of medial hypertrophy (15.6% and 12.1% at 14 and 28 days) and muscularization (65.1% and 42.2% at 14 and 28 days) relative to nontransplanted controls (P <.005 in each case). CONCLUSIONS: Hemodynamic unloading of lungs with pulmonary vascular disease results in progressive normalization of pulmonary artery structure. These results are the first to provide a rationale for attempting to induce regression of pulmonary vascular disease by pressure unloading of the pulmonary circulation. Methods to mechanically unload the pulmonary circulation should be critically evaluated as a strategy for staged surgical repair of congenital heart defects despite presumed irreversible pulmonary hypertension.     

Lung transplantation for pulmonary vascular disease

BACKGROUND: Pulmonary hypertension (PHT) is a lethal condition resulting in markedly diminished life expectancy. Continuous prostaglandin I2 infusion has made an important contribution to symptom management, but it is not a panacea. Lung or heart-lung transplantation remains an important treatment option for end-stage PHT patients unresponsive to prostaglandin I2. This study reviews the outcomes after transplantation for PHT in our program. METHODS: A retrospective chart review was performed for 100 consecutive patients with either primary PHT (48%) or secondary PHT (52%) transplants since 1989. Living recipients were contacted to confirm health and functional status. RESULTS: Fifty-five adult and 45 pediatric patients underwent 51 bilateral lung transplants, 39 single lung transplants, and 10 heart-lung transplants. Mean age was 23.7 years (range, 1.2 months to 54.8 years) and mean pre-transplant New York Heart Association class was 3.2. Pre-transplant hemodynamics revealed a mean right atrial pressure of 9.6+/-5.4 mm Hg and mean pulmonary artery pressure of 64+/-14.4 mm Hg. Hospital mortality was 17% with early death predominantly because of graft failure and infection. With an average follow-up of 5.0 years, 1- and 5-year actuarial survival was 75% and 57%, respectively. Mean pulmonary artery pressure on follow-up catheterization was 22+/-6.0 mm Hg, and mean follow-up New York Heart Association class was 1.3 (p < 0.001 for both compared with pre-transplant). Diagnosis and type of transplant did not confer a significant difference in survival between groups. CONCLUSIONS: Whereas lung or heart-lung transplant for PHT is associated with higher early mortality than other pulmonary disease entities, it provides similar long-term outcomes with dramatic improvement in both quality of life and physiologic aspects.