Effects of angiotensin II receptor antagonist on remodeling of renal arterioles in hypertension

AIM: To investigate the effects of angiotensin II receptor antagonist on remodeling of renal arterioles in hypertension. METHODS: Eighteen 4 weeks old male rats were divided into three groups: Wistar-Kyoto rats (WKY) for normotensive group, and spontaneously hypertensive rats (SHR) for hypertensive group, and SHR treated with losartan orally (15 mg·kg^-1·d^-1). The rats were raised to 16 weeks old. The morphometric parameters of the renal arterioles, and the widths of vascular smooth muscle cells (VSMC) and intercellular space were studied on kidney slices by light microscope and electromicroscope respectively, combined with computer-assistant image analysis system. The minimal renal vascular resistance (RVR_min) was studied by isolated kidney perfusion system. RESULTS: The systolic blood pressure of the tail artery, wall thickness, wall area, ratio of wall thickness to inner diameter, width of VSMC of renal arterioles and RVR_min were all smaller or lower in losartan group than those of SHR.     

Effect of atorvastatin on ventricular remodeling in spontaneous hypertension rats

AIM：To explore the effect of atorvastatin on cardiac remodeling in spontaneous hypertension rats (SHR).METHODS：Twelve spontaneous hypertension rats were divided randomly into two groups：group of atorvastatin (atorvastatin 50 mg·kg^-1·d^-1) and group of SHR (0.5% mucilage of arabic gum,10 mL·kg^-1·d^-1).Additionally,six male Wistar-Kyoto rats (0.5% mucilage of arabic gum,10 mL·kg^-1·d^-1) were selected as control group.Systolic blood pressure was assessed with the tail-cuff method.After six weeks,entire heart,and left ventricle were weighed.The left ventricular weight index was calculated and myocardial hydroxyproline and collagen protein concentration were measured.The serum high sensitivity CRP (hs-CRP) was measured by nephelometry.The localization of vascular cell adhesion molecule (VCAM) in myocardium was investigated by immunohistochemistry assays.The level of NF-κB mRNA expression was detected with in situ hybridization.Ultrastructure in cardiac muscle was also observed under transmission electron microscope.RESULTS：The expression of myocardial VCAM and NF-κB in SHR group was stronger than that in WHY group.Compared with SHR group,entire heart weight,left ventricular weight,left ventricular weight index,serum hs-CRP,myocardial hydroxyproline and collagen protein concentration was decreased,the expression of myocardial VCAM and NF-κB in SHR group was weaker than that in atorvastatin treatment group.The myocardial pathological change such as incomplete karyotheca in cardiac muscle cells,no clear of transverse striation and the mess in myofibril alignment,and hyperplasy in interstitial collagen fibre were observed in SHR group and these changes were improved in atorvastatin treatment group.CONCLUSION：The cardiac remodeling in SHR is improved by atorvastatin.The molecular mechanism may be related to its down-regulating the expression of VCAM protein and NF-κB and inhibiting myocardial chronic inflammation.     

Chinensis lour alkaloids alleviates vascular remodeling in renal hypertensive rats

AIM: To investigate the effect of lobelia chinensis lour alkaloids (LCLAs) on vascular remodeling in renal hypertension.METHODS: The Glodblatt renovascular hypertension model was induced in rats by two-kidney one clip method. The renin activity (PRA) in plasma was determined by radioimmunoassay 8 weeks after the treatments with LCLAs or catoprill. The parameters of vascular remodeling, including media thickness (MT), luminal internal diameter (LD), ratio of MT/LD and ratio of media cross-sectional area to lumen area (MSCA/LA) were measured through the Weigert staining photos of the abdominal aorta. Expressions of collagen and collagen I were measured respectively by the methods of Masson staining and immunohistochemistry. RESULTS: The PRA was significantly increased in hypertensive rats compared with the sham rats (P<0.05). PRA was significantly reduced in LCLAs group compared to control group. No inhibitory effect on PRA was observed in captopril group. The MT, the ratio of MT/LD, MSCA and the expression of collagen on abdominal aorta were significantly increased in hypertensive rats compared with the sham rats (P<0.05). LCLAs and captopril reduced these parameters raised in hypertensive rats (P<0.05). CONCLUSION: The vascular remodeling occurs in renal hypertensive rats. LCLA inhibits the synthesis of the collagen and reduces PRA, which may alleviate the vascular remodeling in hypertensive rats.     

Effect of angiontensin-(1-7) on development of monocrotaline induced pulmonary arterial hypertension and vascular remodeling

AIM: To investigate the effect of angiotensin-(1-7) ［Ang-(1-7)］ on the development of monocrotaline (MCT) induced pulmonary arterial hypertension and vascular remodeling.METHODS: 60 Sprgue-Dawely rats were randomly assigned into three groups: control group, PAH group and PAH+Ang-(1-7) group. Rats in PAH group and PAH +Ang-(1-7) group received 60 mg/kg MCT injection subcutaneously and after 24 h received either saline or 24 μg·kg-1·h-1 of Ang-(1-7) injection via osmotic minipumps for 4 weeks. These rats in control group were firstly injected saline subcutaneously and then received saline injection via osmotic minipumps.RESULTS: After 4 weeks, in PAH group, right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), percentage of wall thickness (WT%) and percentage of wall area (WA%) of pulmonary artery were significantly increased and NO concentration, the level of endothelial nitric oxide synthase (eNOS), eNOS Ser1177-phosphorylation were significantly decreased compared with control group. However, RVSP, RVHI, WT %, WA % were dramatically decreased in PAH +Ang-(1-7) group and NO concentration, the level of eNOS protein, eNOS Ser1177-phosphorylation were significantly increased compared with PAH group.CONCLUSION: These results suggest that Ang-(1-7) could prevent the development of monocrotaline induced pulmonary arterial hypertension and vascular remodeling, which appears to be associated with up-regulation of NO concentration and the level of eNOS protein, eNOS Ser1177-phosphorylation.     

西瓜噬酸菌血红素氧化酶基因hemO功能研究

在生物体中,血红素氧化酶(Heme oxygenase,HemO)在血红素代谢、铁循环和氧化应激等过程中发挥重要作用。在一些病原菌中,血红素氧化酶可参与调控其致病能力。在西瓜噬酸菌(Acidovorax citrulli)中,存在一个编码血红素氧化酶的基因hemO,然而其功能尚未可知。以西瓜噬酸菌Aac5菌株为研究对象,通过基因敲除构建hemO缺失突变体菌株,分析致病力及生物学表型,并检测致病相关基因表达量,初步探究HemO在西瓜噬酸菌中的功能。结果表明,hemO基因缺失会促进菌株生物膜的形成,并导致菌株运动性、生长能力、致病力降低,显著影响致病相关基因的表达,但不影响病原菌诱导烟草过敏性反应的能力。这表明hemO基因参与西瓜噬酸菌的致病力调控过程。     

Changes of hypoxia inducible factor 1 alpha and heme oxygenase 1 in the process of hypoxic pulmonary hypertension development in rats

AIM: To observe the expression of hypoxia inducible factor-1α (HIF-1α) gene and heme oxygenase-1 (HO-1) gene in pulmonary arteries in hypoxic rats. METHODS: Forty male Wistar rats were exposed to hypoxia for 0, 3, 7, 14 or 21 days. Mean pulmonary pressure (mPAP), vessel morphometry, right ventricle hypertrophy index (RVHI) were measured. Lungs were either inflation fixed for immunohistochemistry and in situ hybridization or frozen for later measurement of HO-1 enzyme activity. RESULTS: During hypoxia, mPAP increased to significantly higher values than the control values after 7-day of hypoxia，reaching its peak after 14-day of hypoxia, then remained on the high level. Pulmonary artery remodeling developed significantly after 14-day of hypoxia. Expression of HIF-1α protein in control was poorly positive, but was up-regulated in pulmonary arterial tunica intimae of all hypoxic rats. In pulmonary arterial tunica media, the levels of HIF-1α protein were markedly up-regulated after 3-day and 7-day of hypoxia, then tended to decline after 14-day and 21-day of hypoxia. HIF-1α mRNA staining was poorly positive in control, hypoxia for 3 days and hypoxia for 7 days, but began to enhance significantly after 14-day of hypoxia, then remained stable. Expression of HO-1 protein began to increase after 7-day of hypoxia, reaching its peak after 14-day of hypoxia, then remained stable. Expression of HO-1 mRNA began to increase after 3-day of hypoxia, reaching its peak after 7-day of hypoxia, then declined. CONCLUSION: HIF-1α and HO-1 are both involved in the pathogenesis of hypoxia-induced pulmonary hypertension in rats. Furthermore, HIF-1α may inter-regulate with HO-1 gene in this process.     

Effect of diltiazem on heme oxygenase-1 and nitric oxide synthase in rats with pulmonary hypertension

AIM: To investigate the action of diltiazem (a calcium antagonist) on the expression of heme oxygenase (HO) -1 and nitric oxide synthase (NOS) in the small pulmonary arteries (SPA) of rat in chronic hypoxia. METHODS: Chronic pulmonary arterial hypertension models were established by treating the rats in hypoxic environment for 6 weeks. After 2 weeks of hypoxia, rats were treated with diltiazem (15 mg/kg/day). Right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) were measured. Pathological changes in the lungs were observed under the light microscope and transmission electron microscope. The expression and distribution of heme oxygenase (HO) -1, endothelial NOS (eNOS) and inducible NOS (iNOS) were tested by immunohistochemistry and Western blot. Guanosine-3', 5'-cyclic monophosphate (cGMP) of lung tissues were detected with radioimmunoassay. RESULTS: Diltiazem significantly decreased abnormal RVSP, and RVHI in model rats, attenuated the SPA media thickeness, and recovered abnormal eNOS and iNOS expression in SPA. Whereas diltiazem had little effect on the increased HO-1 expression in SPA caused by hypoxia and ultrastructure injury in endothelium. cGMP levels were corresponded with HO-1. CONCLUSION: Diltiazem has a significant effect on inhibiting hypoxic pulmonary hypertension structural remodeling. These effects might be partly attributed to the suppression of iNOS, promotion of eNOS, and not attenuation HO-1 expression in the lung of hypoxic rats.     

Effect of doxycycline on matrix metalloproteinase activity and vascular remodeling in balloon-injured rat carotid arteries

AIM:To examine the inhibition of matrix metalloproteinase (MMP) activity by doxycycline (Doxy) and its effect on vascular smooth muscle cells (SMCs) proliferation,neointimal hyperplasia and vascular remodeling.METHODS: The model of rat common carotid artery injury was established by balloon-dilatation.Doxy was administered to the animals of treatment group at dose of 30 mg·kg^-1·d^-1.The activity of MMPs in the tissue of injured carotid arteries was measured by gelatin zymography.The thickness and area of neointimal,lumen area and the proliferation of SMCs were measured by histological and morphometric analysis.RESULTS:1.After Doxy treatment,the activity of MMP-9 in the carotid arteries was reduced by 26.3% and 34.5% compared to that in rats without Doxy treatment at 24 hours and 3 days after balloon injury,respectively (P<0.01).The activity of MMP-2 was also reduced by 40.0% at 7 days after injury (P<0.01).2.The thickness of neointimal were significantly decreased by 32.0% and 38.8% (P<0.01) and the lumen area was increased by 58.0% and 90.4 % at 14 and 28 days after injury in the Doxy-treated rats compared to those in control rats,respectively (P<0.01).Doxy treatment significantly reduced intimal SMCs proliferation from 62.76%±1.02 % in the controls to 43.23%±1.06% at 7 days after injury (P<0.01).CONCLUSION: Doxy treatment inhibits the activity of MMPs,the SMCs proliferation of intimal,neointimal hyperplasia and vascular remodeling,suggesting that Doxy treatment is useful in preventing restenosis after PTCA.     

Role of heme oxygenase in cholecystokinin octopeptide ameliorating acute lung injury induced by lipopolysaccharide

AIM: To study the role of heme oxygenase (HO)-1 in the mechanism of cholecystokinin-octapeptide (CCK-8) for attenuation of acute lung injury (ALI) induced by lipopolysaccharide (LPS).METHODS: Adult male rats were randomly divided into five groups: control group,LPS group,CCK-8+LPS group,LPS+ Hm (hemin,HO-1 donor) group and LPS+ZnPP (zinc protoporphyrin,specific inhibitor of HO-1) group.PMN number in bronchoalveolar lavage fluid (BALF),the structure of the lung,MDA content,HO-1 activity,the expressions of HO-1 mRNA and protein in the lung were detected respectively.RESULTS: The lung injury in LPS group was observed,at the same time the numbers of PMN,the content of MDA,the activity and the expression of HO-1 were all higher than those in control group (all P<0.05).The degree of lung injury,PMN numbers and MDA content were lower,while the activity and the expression of HO-1 in CCK-8+LPS and LPS+Hm group were higher than those in LPS group (all P<0.05).However,the degree of lung injury,PMN numbers and MDA content were higher,the activity and the expression of HO-1 were lower in LPS+ZnPP than those in LPS group respectively (all P<0.05).CONCLUSION: CCK-8 attenuates the LPS-induced ALI by means of anti-oxidation and inhibits PMN aggregation,which are both mediated by HO-1 partly.     

Effects of short-chain acyl-CoA dehydrogenase on hypertensive vascular remodeling

AIM: To investigate the changes of short-chain acyl-CoA dehydrogenase (SCAD) in hypertensive vascular remodeling and to explore the relationship between SCAD and vascular remodeling in hypertension.METHODS: The spontaneously hypertensive rats (SHR; 24 weeks old) and Wistar rats (24 weeks old) were used as experimental control groups. The SHR and Wistar rats of 16 weeks old were trained by swimming as experimental groups. The systolic pressure was measured periodically. The thickness of vascular wall and the diameter of the vascular lumen were measured. The contents of ROS and ATP, the enzyme activity of SCAD, and the expression of SCAD at mRNA and protein levels in the aorta were determined. The free fatty acid in the serum and aorta was also measured.RESULTS: Compared with Wistar group, the diameter of vascular lumen decreased in SHR group. The thickness of vascular wall, the ratio of vascular wall and the diameter of vascular lumen, and the blood pressure in SHR group were increased significantly (P<0.05). Compared with SHR group, the diameter of vascular lumen increased in SHR+swim group. The thickness of vascular wall, the ratio of vascular wall and the diameter of vascular lumen, and the blood pressure in SHR+swim group were decreased significantly. Compared with control group, the expression of SCAD at mRNA and protein levels, the enzyme activity of SCAD, and the content of ATP were decreased in SHR group. However, the free fatty acid in the serum and aorta, and the content of ROS in the aorta were increased in SHR group. The expression of SCAD at mRNA and protein levels, the enzyme activity of SCAD, the content of ATP were increased in Wistar+swim group and SHR+swim group. However, the free fatty acid in serum and aorta, and the content of ROS in the aorta were decreased in Wistar+swim group and SHR+swim group.CONCLUSION: Decrease in SCAD expression may be associated with hypertensive vascular remodeling. Swimming training can reverse hypertensive vascular remodeling by increasing the expression of SCAD in the aorta.     

Role of vascular NAD(P)H oxidase in vascular remodeling

NAD(P)H oxidase was initially found in phagocytes and it participates in the generation of reactive oxygen species(ROS). Recent researches have showed that NAD(P)H oxidase also expresses in other tissues including blood vessels and it plays a critical role in vascular remodeling through ROS which are important signaling molecules in vascular cells.This article reviews the biochemical characterization, activation paradigms, structure, and function of this enzyme.     

Changes of heme oxygenase-carbon monoxide system-in vascular calcification in rats

AIM:To investigate the change of heme oxygenase (HO)-carbon monoxide (CO)-cyclic guanosine monophosphate (cGMP) pathway in vascular calcification, to clarify the cellular and molecular mechanimsm in vascular calcification.METHODS:Vascular calcification model was established in rats by using vitamin D₃ and nicotine. The relative content of HO-1 mRNA, immunochemistry (IH) for HO-1, HO activity, HbCO formation and content of cGMP in aorta were measured.RESULTS:Compared to those of control rats, the HO-1 mRNA level in vessels of rats in VDN group(vascular calcification group) were decreased by 34.9% (P＜0.05);expression of HO-1 protein were decreased too, there were trace positive staining of HO-1 in the endothelium, and no obvious immunoreactivity in the medial layer;HO-1 activity was decreased by 60.6% (P＜0.01), CO concentration was decreased by 53.9% (P＜0.01) and cGMP content was decreased by 77.1% (P＜0.01) in vessels of rats in VDN group.CONCLUSION:There were obvious down regulation in HO-CO-cGMP pathway in calcified vessels.     

Effects of grape seed procyanidin on vascular remodeling in renovascular hypertensive rats

AIM: To study the effect of grape seed procyanidin (GSP) on vascular remodeling in renovascular hypertensive (RH) rats. METHODS: The RH rat model was established by two-kidney one-clip method. Two weeks after operation, 28 rats were selected according to the increased tail systolic pressure above 130 mmHg and randomly divided into 4 groups (n=7): RH model group, low GSP treatment group (50 mg·kg^-1·d^-1),high GSP treatment group (200 mg·kg^-1·d^-1) and captopril treatment group (30 mg·kg^-1·d^-1). Meanwhile, 7 rats with sham operation served as controls. Tail systolic pressure, medial thickness (MT), luminal diameter (LD), and the ratio of MT to LD in thoracic aortic wall were determined 6 weeks after treatment. Masson staining and ELISA were used to detect the content of collagen and angiotensin II (Ang II) in aortic tissues. The protein expression of tumor necrosis factor α (TNF-α) in abdominal aortic tissues was determined by Western blotting. RESULTS: Compared with control group, the tail systolic pressure, MT, MT/LD, the content of collagen and the protein expression of TNF-α in aorta were significantly increased in RH model group, but LD decreased. Treatment with GSP and captopril reduced the raised parameters, and increased the LD in RH model rats. These effects were more notable in high GSP treatment group, and equal to captopril treatment group. CONCLUSION: GSP treatment significantly decreases tail systolic pressure in RH rats, and effectively attenuates arterial vascular remodeling by decreasing the content of AngII and reducing the protein expression of TNF-α in aorta.     

Effects of miR-124 over-expression on right ventricular remodeling in rats with pulmonary hypertension

AIM: To investigate the effect of microRNA-124 (miR-124) over-expression mediated by adeno-associated virus (AAV) on right ventricular remodeling in rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). METHODS: Male SD rats (n=32) were randomly divided into 4 groups:normal control (control) group, MCT+normal saline (NS) group, MCT+AAV-GFP (MCT+GFP) group and MCT+AAV-miR-124 (MCT+miR-124) group. The rats in the latter 3 groups were instilled slowly with 100 μL NS, AAV-GFP and AAV-miR-124 by orotracheal instillation after anesthesia, respectively. Three weeks later, MCT (60 mg/kg) was intraperitoneally injected to establish the PAH model. Right ventricular systolic blood pressure (RVSP) and mean arterial pressure of the rats were measured, and right ventricular hypertrophy index (RVHI) and right ventricular weight index (RVWI) were calculated. The pathological sections of the right heart were stained with Sirius red, and the pathological changes of myocardium were observed under a microscope. The expression of miR-124 in the lung tissues was detected by RT-qPCR. The protein levels of transforming growth factor-β₁(TGF-β₁) and p-Smad2 in right heart tissues were determined by Western blot. RESULTS: Compared with control group, RVSP, RVHI, RVWI and the protein levels of TGF-β₁ and p-Smad2 in MCT+NS group and MCT+GFP group were significantly increased (P<0.05), the right ventricular myocytes were significantly enlarged, and collagen deposition was significantly increased. However, compared with MCT+GFP group, RVSP, RVHI, RVWI and the protein levels of TGF-β₁ and p-Smad2 in MCT+miR-124 group were significantly decreased (P<0.05), the degree of right ventricular myocyte hypertrophy was significantly reduced, and collagen deposition was significantly reduced. CONCLUSION: Over-expression of miR-124 obviously reduces RVSP of rats induced by MCT and relieves myocardial remodeling, which may be related to the down-regulation of TGF-β₁ and p-Smad2.     

Effect of polidatin on the activity of phospholipase A2and pulmonary structural remodeling in rats with hypoxia-induced pulmonary hypertension

AIM: To study the relationship between the activity of phospholipase A₂ (PLA₂) and pulmonary structural remodeling with the model of chronic isobaric hypoxic pulmonary hypertension. METHODS: 29 healthy Sprague-Dawley rats were randomly divided into normal control group, chronic hypoxic group and hypoxia plus Polidatin (PD) group. By diameter, the arteries were divided into two groups: arteries of group I (30 μm-100 μm) and group II (101 μm-200μm). The mean pulmonary arterial pressure (mPAP) was measured by inserting a microcatheter into the pulmonary artery. The PLA₂ activity was measured with modified microtitrimetic method. The pulmonary tissue and arterioles morphology changes were examined under light microscope. RESULTS: It was found that after 21 days hypoxia, the mean pulmonary arterial pressure (mPAP), the PLA₂ activity in blood and lung homogenate increased significantly. The media thickness of group I arteries increased (P<0.01) while that of group II arteries had no significant changes. The ratio of media area and adventitia of both groups was raised. Under light microscope, it was observed that pulmonary vascular endothelium proliferated, media became thickening and adventitia matrix increased. Pretreatment with PD could attenuate the changes mentioned above. CONCLUSION:PLA₂ plays an important inducing role through promotion of the pulmonary vascular structural remodeling in the formation of chronic hypoxic pulmonary hypertension.     

The expression of heme oxygenase-1 in vascular smooth muscle cells induced by lipopolysaccharide

AIM:To study the alterations of heme oxygenase-1 mRNA in vascular smooth muscle cells(VSMC) induced by lipopolysaccharide(LPS) and the role of heme oxygenase(HO)/carbon monoxide(CO)pathway in the disorders of regulation of cardiovascular system by LPS. METHODS: LPS (final concentrations 10 mg/L,30 mg/L and 50 mg/L) was added in cultured VSMCs for 6 h respectively or 10 mg/L LPS for 9 h and 18 h. MDA content, LDH release and the rate of trypan blue uptake of VSMC were measured. HO-1 mRNA expression was examined by Northern Blot. RESULTS:VSMC HO-1 mRNA expression was increased gradually with the increasing of LPS concentration. When final concentration of LPS was 50 mg/L, the HO-1 mRNA expression of VSMC was increased by 176.7% compared with control. When LPS final concentration was 10 mg/L, the HO-1 mRNA expression increased gradually along with the culture time. When cultured for 18 h, the HO-1 mRNA expression of VSMC was increased by 195.6% compared with control. Only at LPS 50 mg/L for 6 h and 10 mg/L for 18 h, the rate of trypan blue uptake,MDA content and LDH release were significantly increased. CONCLUSION: LPS can induce the HO-1 mRNA expression of VSMC and that were dose-dependent and time-dependent. The inducible HO may play an important role in the pathogenesis of vascular system under LPS.     

Effect of airway remodeling on airway responsiveness in asthmatic guinea pigs

AIM: To establish a guinea pig asthma model and to evaluate the effect of airway remodeling on airway responsiveness. METHODS: The guinea pig asthma model was established by ovalbumin (OVA) sensitization and challenge repeatedly. Bronchial provocation tests were conducted through intravenous injection of acetylcholine. The airway morphologic parameters were measured by computer image analysis system. White blood cells and the differential count in bronchoalveolar lavage fluid (BALF) were examined. RESULTS: The resistance of airway was increased significantly after 4 weeks of OVA exposure, but the increase disappeared upon prolonged exposure. After 8 weeks of OVA exposure, fiber tissue in large airway was increased, and the thickness of smooth muscle layer of small airway was enlarged, as compared with that in control animals. CONCLUSION: Airway responsiveness has changed after prolonged OVA exposure in guinea pigs. This change is related to airway remodeling.