Lack of synergistic effect of molsidomine and sildenafil on development of pulmonary hypertension in chronic hypoxic rats

The present study addressed whether combined treatment with a phosphodiesterase type 5 inhibitor, sildenafil, and a nitric oxide donor, molsidomine, prevents development of pulmonary hypertension in chronic hypoxic rats. Two weeks of hypoxia increased right ventricular systolic pressure, and right ventricular and lung weight. Treatment with either sildenafil (10 mg/kg/day) or molsidomine (15 mg/kg/day) in drinking water reduced right ventricular systolic pressure and weight, while lung weight was unchanged. Combining sildenafil and molsidomine did not have additional effects compared to molsidomine alone. The number of muscularized pulmonary arteries with diameters below 50 microm was increased in vehicle and sildenafil-treated, but not in molsidomine-treated hypoxic rats. Acetylcholine relaxation was blunted in arteries from vehicle and molsidomine-treated, but not in sildenafil-treated rats. In conclusion, both sildenafil and molsidomine blunts pulmonary hypertension and right ventricular hypertrophy in chronic hypoxic rats, but no synergistic effects were observed.     

Long-acting phosphodiesterase 5 inhibitor, tadalafil, and superoxide dismutase mimetic, tempol, protect against acute hypoxia-induced pulmonary hypertension in rats

Long-acting phosphodiesterase 5 (PDE5) inhibitor, tadalafil, was recently approved for the treatment of pulmonary hypertension. Apart from being a PDE5 inhibitor, tadalafil also possesses antioxidant activity. The aim of this study was to probe whether tadalafil has any beneficial effect over tempol owing to its antioxidant action in addition to PDE5 inhibitory activity. Albino Wistar rats were pretreated with tadalafil (10 mg/kg) or vehicle 2 h before hypoxic exposure, whereas tempol (20 mg/kg) was given 5 min before induction of hypoxia. Right ventricular systolic pressure (RVSP), mean arterial pressure (MAP), heart rate (HR), right ventricular contractility (RVdP/dtmax) and cardiac output (CO) were recorded while subjecting rats to acute hypoxia for 30 min. Lipid peroxidation and reduced glutathione were estimated in serum before and after hypoxia exposure. Tadalafil as well as tempol significantly prevented hypoxia-induced rise in RVSP (p < 0.001) and RVdP/dtmax (p < 0.05). Both tadalafil and tempol pretreatment partially prevented (p < 0.01) the rise in CO due to hypoxia. Tadalafil did not produce any significant change in MAP, whereas tempol led to a significant fall (p < 0.01) in MAP. Acute hypoxia increased the oxidative stress levels. Tadalafil pretreatment partially prevented hypoxia-induced oxidative stress, while tempol pretreatment completely prevented hypoxia-induced oxidative stress. Results suggest that tadalafil because of its antioxidant action in addition to PDE5 inhibitory activity is more appropriate for the prevention of hypoxic pulmonary hypertension than tempol. Tempol also produced undesirable systemic hypotension as side effect, which was not seen with tadalafil because of its pulmonary selective action.     

CPU0213, a non-selective ETA/ETB receptor antagonist, improves pulmonary arteriolar remodeling of monocrotaline-induced pulmonary hypertension in rats

1. The aim of the present study was to explore the effects of CPU0213, a dual endothelin ET(A)/ET(B) receptor antagonist, and nifedipine, a calcium antagonist, in relieving pulmonary hypertension (PH). Both endothelin receptor and calcium antagonists have been reported to be effective in alleviating the remodelling of pulmonary arteries induced by monocrotaline (MCT) in rats. 2. After an initial single dose of 60 mg/kg, s.c., MCT, CPU0213 was administered to rats at doses of 25, 50 or 100 mg/kg, p.o., for 28 days. In addition, nifedipine was administered to another group of rats at a dose of 10 mg/kg, p.o., for 28 days. The haemodynamics of the right ventricle, pulmonary vascular activity, remodelling of the pulmonary arterioles (< 150 microm) and biochemical changes were evaluated. 3. Right ventricular systolic pressure (RVSP), central venous pressure (CVP), the maximum rate of uprising pressure (dP/dT(max)) and the weight index of the right ventricle were significantly elevated in MCT-treated rats. In addition, increases in pulmonary endothelin-1, malonyldialdehyde (MDA) and hydroxyproline content and a reduction in superoxide dismutase activity was found after MCT treatment. The thickness and area of the pulmonary arterial wall were significantly increased in MCT-treated rats compared with control rats. At all three doses tested, CPU0213 ameliorated these changes in a dose-dependent manner and the effects were associated with a greater reduction in the remodelling of pulmonary arterioles. However, nifedipine was only partially effective in amelerioating biochemical and haemodynamic changes induced by MCT, significantly reducing RVSP, CVP, +dp/dt(max), tissue MDA, inducible nitric oxide synthase and hydroxyproline content, increasing -dp/dt(min) and having no effect on the other parameters investigated. In addition, nifedipine had no effect on remodelling of the arterial wall. 4. In conclusion, CPU0213 is more effective than nifedipine in suppressing the remodelling of pulmonary arterioles in PH induced by MCT treatment of rats. Furthermore, CPU0213 may have promise in treating PH secondary to connective tissue disease.     

Hypoxia-induced pulmonary vascular remodeling and right ventricular hypertrophy is unaltered by long-term oral L-arginine administration

Nitric oxide has been shown to reduce the development of chronic hypoxic pulmonary hypertension. L-arginine is the substrate for endogenous nitric oxide synthesis. The aim of this study was to investigate whether oral L-arginine prevents the development of pulmonary vascular and right ventricular hypertrophy in adult chronic hypoxic rats. Male rats were maintained in either normoxic or hypobaric hypoxic (10% O(2)) chambers for two weeks as controls or treated with L-arginine (2 g kg(-1) day(-1) in the drinking water). Both in vehicle and L-arginine-treated rats, chronic hypoxia caused right ventricular hypertrophy, increased media to lumen ratio and increased lung weight. Contraction to the thromboxane analogue, U46619, was increased in intrapulmonary arteries, while systemic blood pressure was unaltered. Relaxations induced by the nitric oxide donor, S-nitroso-N-acetylpenicillamine (SNAP), were increased in arteries from L-arginine-treated normoxic and hypoxic animals. In conclusion, long-term oral L-arginine administration fails to prevent development of right ventricular hypertrophy and vascular media hypertrophy in adult chronic hypoxic rats.     

Effects of the endothelin ET(A) receptor antagonist, TA-0201, on pulmonary arteries isolated from hypoxic rats.

To investigate the roles of endothelin-1 in the pathogenesis of hypoxic pulmonary hypertension, we studied the effects of a selective endothelin ET(A) receptor antagonist, TA-0201 (N-(6-(2-(5-Bromopyrimidin-2-yloxy) ethoxy)-5-(4-methylphenyl) pyrimidin-4-yl)-4-(2-hydroxy-1,1-dimethylethyl) benzensulfonamide sodium salt sesquihydrate), on helical strips of pulmonary arteries isolated from hypoxia-induced pulmonary hypertensive rats as compared with those of normoxic rats. Endothelin-1-induced maximum contractions were significantly inhibited by exposure to hypoxia in the pulmonary arterial strips, but not in the mesenteric arterial strips. The hypoxia also induced right ventricular hypertrophy in rats. Addition of TA-0201 to the bath inhibited the endothelin-1-induced contraction of pulmonary arterial strips isolated from hypoxic rats more effectively than in those of normoxic rats. Oral administration of TA-0201 to hypoxic rats inhibited the hypoxia-induced right ventricular hypertrophy, and decreased the maximum contractile response to endothelin-1 in pulmonary arterial strips isolated from these rats. Those inhibitory effects induced by the oral administration of TA-0201 were not observed in the pulmonary arteries from normoxic rats or in the mesenteric arteries from both hypoxic and normoxic rats. These results suggest that endothelin-1 has important pathophysiological roles in hypoxia-induced pulmonary hypertension, and that TA-0201 may inhibit the endothelin-l-induced contraction through a change in the function of endothelin ET(A) receptor as well as competitive inhibition for endothelin ET(A) receptor.     

川芎嗪对慢性缺氧高二氧化碳大鼠肺动脉高压的影响

研究川芎嗪对大鼠慢性缺氧、慢性缺氧伴高二氧化碳所致肺动脉高压的作用及对心肌力学指标和动脉血氧分压的影响。结果表明，川芎嗪（ＴＭＰＺ）８０ｍｇ·ｋｇ－１能显著抑制由慢性缺氧、慢性缺氧伴高二氧化碳所致肺动脉升压反应及右心室收缩压，而对右心室ＲＶ±ｄＰ／ｄｔｍａｘ、动脉血氧分压都无明显影响。提示川芎嗪能降低慢性缺氧高二氧化碳大鼠的肺动脉压力，而不降低动脉血氧分压，且对右心功能具有保护作用，是一种降低慢性阻塞性肺部疾病肺动脉高压的理想药物。     

3',4'-Dihydroxyflavonol restores endothelium-dependent relaxation in small mesenteric artery from rats with type 1 and type 2 diabetes

Diabetes is known to cause an overproduction of reactive oxygen species (ROS), contributing to the impairment of endothelium-dependent relaxation in microvasculature, however it is not clear whether antioxidants are able to reverse microvascular endothelial dysfunction. The aim of this study is to investigate whether the synthetic flavonol 3',4'-dihydroxyflavonol (DiOHF) could reduce the levels of reactive oxygen species (ROS) and improve endothelium-dependent relaxation in mesenteric arteries from both type 1 and type 2 diabetic rats. Endothelial function of third order mesenteric arteries from type 1 and type 2 diabetic rats was assessed using wire-myography. Superoxide levels in the mesenteric arteries were measured by L-012-induced chemiluminescence. Mesenteric arteries from type 1 and type 2 diabetic rats had elevated levels of superoxide production compared to control, which was accompanied by impaired responses to the endothelium-dependent relaxant, acetylcholine (ACh). The acute presence of DiOHF ex vivo significantly reduced the superoxide levels in the diabetic mesenteric arteries and restored endothelial function. The antioxidant activity of DiOHF is comparable to superoxide dismutase mimetics (tempol and MnTMPyP), which also significantly reduced the superoxide levels and improved endothelial function in diabetic arteries. Therefore, the synthetic flavonol DiOHF could effectively reduce oxidant stress and restore microvascular endothelium-dependent relaxation in diabetic rats.     

Acute and chronic effects of T-1032, a novel selective phosphodiesterase type 5 inhibitor,on monocrotaline-induced pulmonary hypertension in rats

We examined the hemodynamic property of T-1032 (methyl 2-(4-aminophenyl)-1,2-dihydro-1-oxo-7-(2-pyridylmethoxy)-4-(3,4,5-trimethoxy-phenyl)-3-isoquinoline carboxylate sulfate), a novel selective phosphodiesterase type 5 (PDE5) inhibitor, and evaluated the chronic effect of T-1032 on cardiac remodeling and its related death in monocrotaline (MCT)-induced pulmonary hypertensive rats. T-1032 (1, 10, 100 micro g/kg, i.v.) significantly reduced mean arterial pressure (MAP) and right ventricular systolic pressure (RVSP) without a change in heart rate. The change in RVSP was more potent than that in MAP with 1 micro g/kg T-1032 treatment (RVSP: -8.2+/-1.2%, mean arterial pressure: -5.7+/-1.2%), and reductions in RVSP and MAP reached a peak at doses of 1 and 10 micro g/kg, respectively. In contrast, nitroglycerin (0.1, 1, 10 micro g/kg, i.v.) and beraprost (0.1, 1 micro g/kg, i.v.) did not cause a selective reduction in RVSP at any dose. When T-1032 (300 ppm in diet) was chronically administered, it delayed the death, and significantly suppressed right ventricular remodeling (T-1032-treated: 0.318+/-0.021 g, control: 0.401+/-0.013 g, p<0.05). Our present results suggest that T-1032 selectively reduces RVSP, and resulting in the suppression of right ventricular remodeling with a delay of the death in MCT-induced pulmonary hypertensive rats.     

血晶素对缺氧大鼠肺组织PDGF-B基因表达的影响

目的　研究血晶素对大鼠肺组织血小板源性生长因子B链 (PDGF B)基因表达的影响 ,探讨血晶素降低缺氧大鼠右心室收缩压 (RVSP)和改善缺氧性肺血管重构的机制。方法　用右心导管检测RVSP ;以双波长分光光度法测定动脉血中碳氧血红蛋白 (COHb)的含量 ;用免疫组织化学染色观察PDGF B、增殖细胞核抗原 (PCNA)蛋白的表达 ;用原位杂交检测PDGF BmRNA的定位并用图象分析检测其水平。结果　①正常大鼠肺腺泡内动脉 (IAPA)管壁PDGF BmR NA原位杂交及PDGF B、PCNA免疫组织化学染色结果为阴性 ,而缺氧大鼠的上述实验结果均为阳性 ,同时缺氧大鼠动脉血中COHb的含量较正常对照组大鼠高 1 8倍 (P <0 0 1)。②血晶素可使动脉血中COHb含量较单纯缺氧组进一步增多 (P <0 0 5 ) ,抑制缺氧大鼠RVSP的升高 (P <0 0 1) ,肺组织IAPA管壁PDGFmRNA原位杂交及PDGF B、PCNA免疫组织化学染色虽为阳性 ,但弱于单纯缺氧组 ,经图像分析差异有显著性 (P <0 0 1或 0 0 5 )。结论　血晶素促进内源性CO的产生 ,使缺氧大鼠肺组织PDGF B基因表达下调 ,间接地抑制缺氧状态下血管壁平滑肌细胞过度增殖引起的肺血管重构 ,这可能是血晶素改善大鼠缺氧性肺动脉高压的原因之一     

Alterations in pulmonary vascular function in rats exposed to intermittent hypoxia

Vasoactive agents were examined in arteries from control rats and rats exposed to intermittent hypoxia (10% oxygen; 8 h/day) for 3, 5 or 20 days. Hypoxic rats developed right ventricular hypertrophy after 5 days, but became pulmonary hypertensive (elevated right ventricular systolic pressure; RVSP) only after 20 days. In pulmonary arteries (main and intralobar), responses to acetylcholine and ionomycin (endothelium-dependent vasodilators) were reduced after 20 and 5 days of intermittent hypoxia, whereas contractions to 5-hydroxytryptamine (5-HT) were enhanced (potency increase >10-fold) after 20, 5 and 3 days. Contractions to endothelin-1 and a thromboxane-mimetic, but not Ca(2+), were also increased. No changes in vascular function occurred in aorta. Since changes in pulmonary vascular function preceded the increase in RVSP they do not result from, but may contribute to, the development of hypoxia-induced pulmonary hypertension. If similar changes occur in humans, they may be important in conditions characterised by intermittent, as opposed to continuous, hypoxia.     

硫化氢抑制低氧性肺动脉高压大鼠肺动脉弹力蛋白的表达

目的　探讨硫化氢 (H2 S)抑制低氧性肺动脉高压(HPH)大鼠肺动脉弹力蛋白表达的变化。方法　将Wistar大鼠 2 4只随机分为 :对照组 (n =8) ,低氧组 (n =8) ,低氧 +硫氢化纳 (NaHS)组 (n =8) ,以右心导管测定 3组大鼠肺动脉平均压 (mPAP) ,分离右心室 (RV)和左心室加室间隔 (LV+S) ,计算RV/LV +S比值 ,并以光学显微镜观测肺血管结构变化 ,用免疫组织化学方法研究弹力蛋白和转化生长因子β(TGF β)在肺动脉平滑肌细胞的表达含量。 结果　低氧组的mPAP和RV/ (LV +S)比值明显高于对照组 (P均 <0 0 1) ,低氧 +NaHS组的mPAP和RV/ (LV +S)比值 ,明显低于低氧组 (P均 <0 0 1) ;低氧组肌型动脉、部分肌型动脉百分比明显高于对照组 (P <0 0 5 ,P <0 0 1) ,非肌型动脉百分比明显低于对照组 (P <0 0 1) ,低氧 +NaHS组肌型、部分肌型动脉百分比明显低于低氧组 (P均 <0 0 1) ,非肌型动脉百分比明显高于低氧组 (P <0 0 1) ;低氧组肺中、小型肺动脉平滑肌细胞弹力蛋白表达含量明显高于对照组 (P均 <0 0 1) ,低氧 +NaHS组肺中、小型肺动脉平滑肌细胞弹力蛋白表达含量明显低于低氧组 (P均 <0 0 1) ;低氧组肺中、小型肺动脉平滑肌细胞TGF β表达含量明显高于对照组 (P均 <0 0 1) ,低氧 +NaHS组肺中、小型肺动脉平滑     

Resveratrol reverses monocrotaline-induced pulmonary vascular and cardiac dysfunction: a potential role for atrogin-1 in smooth muscle

Arterial remodeling contributes to elevated pulmonary artery (PA) pressures and right ventricular hypertrophy seen in pulmonary hypertension (PH). Resveratrol, a sirtuin-1 (SIRT1) pathway activator, can prevent the development of PH in a commonly used animal model, but it is unclear whether it can reverse established PH pathophysiology. Furthermore, atrophic ubiquitin ligases, such as atrogin-1 and MuRF-1, are known to be induced by SIRT1 activators but have not been characterized in hypertrophic vascular disease. Therefore, we hypothesized that monocrotaline (MCT)-induced PH would attenuate atrophy pathways in the PA while, conversely, SIRT1 activation (resveratrol) would reverse indices of PH and restore atrophic gene expression. Thus, we injected Sprague-Dawley rats with MCT (50 mg/kg i.p.) or saline at Day 0, and then treated with oral resveratrol or sildenafil from days 28-42 post-MCT injection. Oral resveratrol attenuated established MCT-induced PH indices, including right ventricular systolic pressure, right ventricular hypertrophy, and medial thickening of intrapulmonary arteries. Resveratrol also normalized PA atrogin-1 mRNA expression, which was significantly reduced by MCT. In cultured human PA smooth muscle cells (hPASMC), resveratrol significantly inhibited PDGF-stimulated proliferation and cellular hypertrophy, which was also associated with improvements in atrogin-1 levels. In addition, SIRT1 inhibition augmented hPASMC proliferation, as assessed by DNA mass, and suppressed atrogin mRNA expression. These findings demonstrate an inverse relationship between indices of PH and PA atrogin expression that is SIRT1 dependent and may reflect a novel role for SIRT1 in PASMCs opposing cellular hypertrophy and proliferation.     

Greater hypertrophy in right than left ventricles is associated with pulmonary vasculopathy in sinoaortic-denervated Wistar-Kyoto rats

1. Biventricular hypertrophy has been described in a high blood pressure variability (BPV) model of sinoaortic-denervated (SAD) rats without systemic hypertension. To explore the possible involvement of the lung in SAD-induced right ventricular hypertrophy (RVH), we examined lung morphology, in addition to systemic haemodynamics and ventricle morphology, in Wistar-Kyoto rats 32 weeks after SAD. 2. In Wistar-Kyoto rats 32 weeks after SAD, there existed a substantial elevation in BPV, with no change in the average level of arterial pressure. Biventricular hypertrophy following SAD was characterized by a greater hypertrophy in right than left ventricles; both absolute and normalized right ventricular weights were significantly increased by 22 and 27%, respectively, and only normalized left ventricular weight was significantly increased by 12%. No infarcts were found in any ventricles examined. 3. In the lung, the most prominent change following SAD was pulmonary vasculopathy, including wall thickening, perivascular fibrosis and cell infiltration. In pulmonary arteries with an internal diameter of 70-130 microm, the external diameter, wall thickness and wall thickness to internal diameter ratio were increased in SAD compared with control rats. 4. There was no correlation between right and left ventricular weights. In contrast with BPV-correlated left ventricular weight, right ventricular weight was correlated with the wall thickness of the pulmonary artery, but not with BPV. 5. These findings suggest that greater RVH following SAD is associated with pulmonary vasculopathy, but is not secondary to the left ventricular problems or high BPV.     

Flow- and acetylcholine-induced dilatation in small arteries from rats with renovascular hypertension--effect of tempol treatment

We investigated whether renovascular hypertension alters vasodilatation mediated by nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) and the influence of the superoxide dismutase mimetic tempol on vasodilatation. One-kidney one-clip hypertensive Sprague-Dawley rats, treated with either vehicle or tempol (from weeks 5 to 10 after placement of the clip), and uninephrectomized control rats were investigated. In renal hypertensive rats systolic blood pressure increased to 171+/-6 mmHg (n=10), while in tempol-treated rats systolic blood pressure remained normal (139+/-7 mmHg, n=5). In isolated pressurized mesenteric small arteries NO-mediated dilatation was obtained by increasing flow rate and EDHF-mediated dilatation by acetylcholine. In arteries from hypertensive rats, flow-induced dilatation was blunted, as compared to normotensive and tempol-treated rats, while acetylcholine-induced dilatation remained normal. Measured by dihydroethidium staining there was an increased amount of superoxide in arteries from vehicle-treated rats, but not from tempol-treated rats. Expression by immunoblotting of endothelial NO synthase and the NAD(P)H oxidase subunit p47phox remained unaffected by high blood pressure and tempol treatment. Simultaneous measurements of NO-concentration and relaxation were performed in isolated coronary arteries from the same animals. As compared to vehicle-treated rats, both acetylcholine-induced relaxation and NO-concentration increased in arteries from tempol-treated animals, while only the relaxation was improved by the NO donor, S-nitroso-N-acetylpenicillamine (SNAP). In conclusion renovascular hypertension selectively inhibits flow-induced NO-mediated vasodilatation, while EDHF-type vasodilatation remains unaffected, suggesting that high blood pressure leads to increased generation of superoxide contributing to decreased NO bioavailability. Furthermore, the abnormal endothelium function can be corrected by tempol treatment, but this seems to involve mechanisms partly independent of NO.     

Rho激酶抑制剂法舒地尔对肺动脉高压大鼠内皮素-1水平的干预研究

目的 探讨Rho激酶抑制剂法舒地尔对肺动脉高压(PH)大鼠内皮素-1水平的干预作用.方法 32只成年Wistar大鼠均分为对照3周组(C3)、PH模型3周组(P3)、6周组(P6)及干预组(F组).予野百合碱建模,第22日始F组予法舒地尔腹腔内注射干预.C3、P3、P6、F组大鼠分别于造模后3、6周末测定大鼠右心室收缩压(RVSP)、血浆内皮素-1 (ET-1)水平,观察肺小动脉病理.结果 ①C3、P3、P6、F组大鼠RVSP分别为(31.2±7.6)、(43.3±8.3)、(56.9±6.9)、(47.3±6.3)mmHg.血浆ET-1分别为(1.09±0.39)、(1.83±0.29)、(2.34±0.65)、(1.90±0.33)ng·mL-1 ;②造模后大鼠RVSP、ET-1随时间延长而升高,法舒地尔干预后上述指标明显下降.③造模后肺小动脉平滑肌增殖,管腔狭窄,F组较P6组管腔明显增大,增殖减轻;④RVSP与ET-1存在明显正相关(r=0.721,P＜0.01).结论 Rho激酶抑制剂法舒地尔能显著降低PH大鼠血浆ET-1水平,有效降低肺动脉压力.     

Effects of cilazapril, a novel angiotensin converting enzyme inhibitor, on the structure of pulmonary arteries of rats exposed to chronic hypoxia.

Chronic hypoxia is known to be associated with a thickening of the media of pulmonary arteries. The goal of the present study was to assess if cilazapril, a novel long-acting angiotensin converting enzyme (ACE) inhibitor, could prevent this thickening. For this purpose, three groups of rats were studied. One group was kept in normal room air. Two other groups were exposed to chronic hypoxia (inspired fraction of oxygen equal to 8% during 4 weeks). One group of hypoxic rats was treated with placebo and the other group received cilazapril (as food admixture of approximately 3 mg/kg/day). After 4 weeks, rats were anesthetized and pulmonary artery pressure and hematocrit measured. Then, the lungs were perfused and fixed and morphometry of the pulmonary arteries was performed. Hypoxia induced an increase in pulmonary artery pressure and hematocrit associated with a dramatic increase in the thickness of the media of the pulmonary arteries. Cilazapril completely prevented the thickening of the media of the pulmonary arteries but did not significantly decrease the pulmonary artery pressure or right ventricular weight.     

Renal protection of in vivo administration of tempol in streptozotocin-induced diabetic rats

The present study was carried out to investigate the protective effects of tempol on renal function and the underlying mechanism in streptozotocin-induced diabetic rats. The diabetic rats were randomly divided into the model group (without tempol) and tempol group (1 mM tempol in drinking water for 6 weeks). Nondiabetic rats were served as the Control group. The mRNA expression of canonical transient receptor potential 6 (TRPC6), transforming growth factor (TGF)-β1, and type IV collagen (Col IV) were examined. The malondialdehyde (MDA) level, activities of superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in renal tissues were measured to assess redox status in kidneys. We found that tempol significantly reduced 24-h urine output and urine albuminuria excretion in the diabetic rats. Compared with the model group, the concentration of MDA was significantly lower in the tempol group. In addition, diabetes decreased activities of SOD and GSH-Px and these responses were prevented by tempol treatment. Moreover, in diabetic rats, the mRNA expression levels of TGF-β1 and Col IV were upregulated. TRPC6 mRNA expression level was down-regulated in diabetic kidneys. However, all of these diabetic effects were significantly suppressed by tempol treatment. These results suggest that chronic treatment of diabetic rats with tempol can protect kidneys, possibly by reducing expression of TGF-β1, Col IV, and upregulating TRPC6 expression level.     

硝苯地平对大鼠肺动脉高压的治疗作用及其机制探讨

[目的]探讨硝苯地平对肺动脉高压的治疗作用及其可能机制。[方法]SD雄性大鼠随机分为3组:对照组、模型组和硝苯地平治疗组。缺氧致肺动脉高压模型制作:将大鼠置于氧浓度为10％的常压缺氧箱内,每天8小时,连续4周。治疗组给予口服硝苯地平10 mg/(kg·d),模型组和对照组均给予等量生理盐水,持续4周。4周后,通过静脉插管测定血流动力学,测定右心室和肺脏肥大指数,检测血清及组织中SOD、MDA、NO水平。[结果]用药或生理盐水4周后,模型组右心室压(RVSP)和中心静脉压(CVP)均较正常组显著提高(P<0.01),而治疗组RVSP和CVP较模型组显著降低(P<0.01);经硝苯地平治疗后,均能显著抑制右心室及肺组织肥大;治疗组大鼠血液和组织中SOD和NO较模型组显著升高(P<0.01),而MDA则显著下降(P<0.05)。[结论]硝苯地平对于缺氧性肺动脉高压具有一定的治疗作用,其机制除了钙拈抗作用外,可能还存在抗氧化作用。     

Pharmacological efficacy of CPU 86017 on hypoxic pulmonary hypertension in rats: mediated by direct inhibition of calcium channels and antioxidant action, but indirect effects on the ET-1 pathway

Endothelin-1 (ET-1) plays a key role in the pathogenesis of pulmonary hypertension. The present study was conducted to examine the effects of a novel compound p-chlorobenzyltetrahydroberberine (CPU 86017) on endothelin-1 system of hypoxia-induced pulmonary hypertension in rats. SD male rats were divided into control, untreated pulmonary hypertension, nifedipine (10 mg/kg p.o.), and CPU 86017 (80, 40, and 20 mg/kg p.o.) groups. The pulmonary hypertension was established by housing the rats in a hypoxic (10 +/- 0.5% oxygen) chamber 8 hours per day for 4 weeks. Hemodynamic and morphologic assessment exhibited a significant increase in the central vein pressure (CVP), right ventricular systolic pressure (RVSP), and pulmonary arteriole remodeling in the pulmonary hypertensive rats, which were improved by CPU 86017 80 and 40 mg/kg administration (P < 0.01). The elevated pulmonary endothelin-1 level and the over-active preproET-1 and iNOS mRNA expression were also decreased significantly (P < 0.01) in CPU 86017 groups. The maladjustment of redox enzyme system in pulmonary hypertension rats was corrected after treatment. We concluded that CPU 86017 improves pulmonary hypertension mainly to suppress the endothelin-1 pathway at the upstream and downstream via calcium antagonism and antioxidative action, then, resulting in a relief in pathogenesis of the disease.     

DA-8159, a potent cGMP phosphodiesterase inhibitor,attenuates monocrotaline-induced pulmonary hypertension in rats

In this study, we evaluated the effects of oral administration of DA-8159, a selective phosphodiesterase-5 inhibitor, on the development of pulmonary hypertension (PH) induced by monocrotaline (MCT). Rats were administered either MCT (60 mg/kg) or saline. MCT-treated rats were divided into three groups and received orally administered vehicle, or 1 mg/kg or 5 mg/kg of DA-8159, twice a day for twenty-one days. The MCT group demonstrated increased right ventricular weights, medial wall thickening in the pulmonary arteries, myocardial fibrosis and the level of plasma cyclic guanosine monophosphate (cGMP), along with decreased body weight gains. However, DA-8159 markedly and dose-dependently reduced the development of right ventricular hypertrophy and medial wall thickening. DA-8159 also amplified the increase in plasma cGMP level and significantly increased the level of lung cGMP, compared with the MCT group. Although the body weight gain was still lower from the saline-treated control group, DA-8159 demonstrated a significant increase in body weight gains, in both 1 mg/kg and 5 mg/kg groups, when compared with the MCT group. In myocardial morphology, MCT-induced myocardial fibrosis was markedly prevented by DA-8159. These results suggest that DA-8159 may be a useful oral treatment option for PH.