Role of angiotensin II and angiotensin II receptors in vascular smooth muscle cells migration

AIM:To determine the effects of Angiotensin II(AngII) on migration of rat smooth muscle cells and to investigate the mechanisms underlying Ang II action in the development of injured vascular disease. METHODS:VSMCs isolated from aortic media of Wistar rats and cultured by the modified explant method were adopted. In prersence and absence of AngII, the expression of AngII receptor and reorganization of the actin cytoskeleton of VSMCs were studied by immunocytochemistry technique, fluorocytochemistry technique. The migration assays were performed by a modified Boyden's chamber. And the effects of AT₁R antagonist (CV-11974), AT₂R antagonist (PD123319) on aforementioned target were studied.RESULTS:VSMCs migration was stimulated by addition of AngII. The dynamic reorganization of actin cytoskeleton may be an important mechanism by which AngII facilitates VSMC motility. The expression of AT₁R in VSMCs can be upregulated after treatment with AngII initially, then decreased gradually. The expression of AT₁R was downregulated by AT₁R antagonist. The effect of AngII on VSMCs migration was mediated by AT₁R, while AT₂R had no significant effect.CONCLUSION:The dynamic reorganization of actin cytoskeleton is required for AngII-induced VSMC migration, and this effect is mediated by AT₁R .     

Long-term effects of TCV116 on left ventricular remodeling and heart function after myocardial infarction in rats

AIM: To investigate the effects of long-term TCV116 on left ventricular remodeling and heart function after myocardial infarction. METHODS: Myocardial infarction (MI) was caused by ligation of the left anterior descending coronary artery in rats. One week after the surgical performance, the surviving rats were randomly assigned to the following treatment protocols: (1) MI rats with no therapy; (2) MI rats treated with TCV116 2 mg/kg per day; (3) Sham-operated control; (4) Sham-operated rats, treated with TCV116 2 mg/kg per day. At 22 weeks, cardiac hemodynamic parameters such as MAP, LVSP, dp/dt_max and LVEDP, and histomorphometric parameters such as LVW/BW and LVCA/BW were measured, mRNA of cardiac genes such as βMHC, BNP, TGF-β₁, collagen I and III were quantified, and survival rates were calculated. RESULTS: Compared with sham-operated rats, MI rats without therapy showed significant increases in histomorphometric parameters as well as in mRAN expressions of cardiac genes (P<0.01); While their hemodynamic parameters were significantly impaired (P<0.01), and survival duration shortened (P<0.05). Compared with MI rats without therapy, MI rats treated with TCV116 showed significant attenuation of mRAN expression of cardiac genes (P<0.01); While their hemodynamic parameters were significantly improved (P<0.05 or P＜0.01), and survival duration extended (P<0.05). CONCLUSION: Treatment with long-term angiotensin II type 1 receptor antagonist may improve left ventricular remodeling and cardiac function after MI in rats.     

植物源血管紧张素转换酶抑制剂的研究进展

血管紧张素转换酶抑制剂(Angiotensin converting enzyme inhibitors,ACEI)通过肾素-血管紧张素系统(RAS)和激肽释放酶-肽酶系统(KKS),抑制血管紧张素II的生成,减少缓激肽的降解,从而达到降血压的目的;植物来源的天然化合物具有来源广泛、结构多样、特异性高、毒性低等特点,因而从植物中筛选安全有效的ACEI成为研究热点。在此综述了血管紧张素转换酶(ACE)的活性测定方法以及植物来源的不同结构类型的ACEI研究进展。     

Role of PARP in endothelial cell apoptosis induced by angiotensin Ⅱ

AIM: To explore the role of poly-(ADP-ribose)polymerase (PARP) in the cultured endothelial cell apoptosis induced by angiotensin Ⅱ.METHODS: The cultured endothelial cells were treated with angiotensin Ⅱ at concentration of 1 μmol/L.The apoptosis of endothelial cells was assessed by TUNEL.Meanwhile,the activity of PARP and the content of nitric oxide (NO) were also measured.RESULTS: Angiotensin Ⅱ induced apoptosis in endothelial cells in a time-dependent manner.The content of NO begun to increase at 6 h (P<0.05),and peaked at 24 h.The activity of PARP also increased at 6 h (P<0.05),peaked at 12 h,and was lower than that in the control at 48 h (P<0.05).CONCLUSION: The cytotoxicity of NO has a relevant role in apoptosis of endothelial cells induced by angiotensin Ⅱ,and can increases the activity of PARP.     

Effects of atorvastatin on cardiac myocyte hypertrophy of neonatal rat induced by angiotensinⅡ in vitro and TLR4 expression

AIM: To assess effects of atorvastatin (Ator) on cardiac myocytes (CM) hypertrophy of neonatal rat induced by angiotensinⅡ (AngⅡ) in vitro and Toll like receptor 4 (TLR4) expression for theoretical bases of preventing and treating myocardial hypertrophy.METHODS: CM of neonatal Sprague-Dawley (SD) rats were isolated with trypsin digestion method and those growth-arrested cells were stimulated with 10^-7 mol/L AngⅡ in the presence of various concentrations of Ator.The method of coomassie brilliant blue was adopted to evaluate the protein contents of CM.The changes in β-MHC,AT₁ receptor and TLR4 mRNA expression were observed by RT-PCR.RESULTS: ① AngⅡ increased the protein content of CM and β-MHC mRNA expression significantly,upregulated AT₁ receptor and TLR4 gene expression.② In a dose-dependent manner,Ator inhibited the increases in the protein contents of CM and β-MHC mRNA expression induced by AngⅡ.③ In a dose-dependent manner,Ator downregulated the AT₁ receptor and TLR4 mRNA expression of CM hypertrophy of neonatal rat induced by AngⅡ.CONCLUSION: Ator inhibits CM hypertrophy,downregulates the AT₁ receptor and TLR4 gene expression.     

Effects of puerarin on apelin-12, angiotensin II,NO and blood pressure in renovascular hypertensive rat

AIM: To investigate the effects of puerarin on blood pressure in renovascular hypertensive rats, and to measure puerarin-induced changes of apelin-12, angiotensin II (Ang II) and nitric oxide(NO), the factors related to development of hypertension. METHODS: Sixty-five male Sprague-Dawley rats were used, of which 8 rats were randomly selected as sham operation group, and the remaining were used to make two-kidney, one-clip model. The rats that met the criterion for Goldblatt hypertensive rat model were randomly allocated into 5 groups: high-, middle- and low-dose puerarin groups, captopril group, and model group. The drugs were administered for 6 weeks. Blood pressure was measured every 2 weeks. Six weeks after treatment, all rats were sacrificed under deep anesthesia. Blood and kidney samples were collected. The level of apelin-12 in serum and kidneys was detected by ELISA. The level of Ang II in plasma and kidneys was measured by radioimmunoassay. NO level in serum was examined by nitrate reductase assay. RESULTS: Puerarin had an antihypertensive effect in a dose-dependent manner. Marked decreases in the level of serum apelin-12 in high- and middle-dose puerarin groups were observed(P<0.01). Puerarin at low dose did not cause obvious change in the content of apelin but still reached significant level (P<0.05). As the dose of puerarin went up, the level of apelin-12 in the kidneys was gradually decreased. Puerarin at high and middle doses obviously reduced the level of AngII in plasma, while purarin at low dose did not produce any significant effects. Puerarin at high and middle doses markedly increased the level of NO in serum, but puerarin at low dose did not induce any significant changes. CONCLUSION: Puerarin has an antihypertensive effect, and its mechanism may be related to inducing the changes of apelin, Ang II and NO, and regulating the balance among those factors.     

Changes of neuropeptides and electrolytes in patients with acute traumatic brain injury

AIM: To investigate the levels of neuropeptides and electrolytes in the patients with acute traumatic brain injury.METHODS: Seventy-eight patients with acute brain injury were divided into mild, moderate and severe groups according to their GCS scores. The serum levels of arginine vasopressin (AVP) and angiotensin II (Ang II) were measured on day 1, 3 and 7 after injury. The serum levels of electrolytes were also measured on day 1. Forty-one subjects who received healthy check-up served as normalcontrols. RESULTS: Compared with normal control group, the serum levels of AVP and Ang II significantly increased in the patients with traumatic brain injury (P<0.01), depending on the severity of brain injury. Both neuropeptides reached the peak on day 3 after injury. The concentrations of serum potassium and calcium decreased in the patients with acute brain injury(P<0.01),also showing a severity-dependent tendency. No significant change of serum sodium in the patients with brain injury was observed. CONCLUSION: The serum levels of arginine vasopressin and angiotensin II canalso be used as the severity indicators of traumatic brain injuries. Decrease in serum potassium and calcium can also be used to evaluate the severity in patients with acute traumatic brain injury.     

Characterization of the pharmacokinetic and pharmacodynamic properties of the angiotensin-converting enzyme inhibitor, enalapril, in horses

The pharmacokinetics of enalapril (0.5 mg/kg i.v.) and the pharmacodynamics of enalapril (0.5 mg/kg PO) in 5 mares were investigated. After single i.v. dosing, concentrations of enalapril and enalaprilat, its active metabolite, were measured. Two weeks later, enalapril was administered by nasogastric tube. Potassium, creatinine, blood urea nitrogen (BUN), enalapril, and enalaprilat concentrations and angiotensin converting enzyme (ACE) activity were measured in serum. In addition, heart rate, blood pressure, digital venous blood gases, and lactate were measured. Two weeks later, enalapril was again administered by nasogastric tube. To mimic activation of the renin-angiotensin-aldosterone system, angiotensin I (0.5 microg/kg) was administered at fixed intervals, followed by blood-pressure and heart-rate measurement. The elimination half lives of enalapril and enalaprilat were 0.59 and 1.25 hours, respectively, after i.v. administration. After PO administration, enalapril and enalaprilat were not detectable in serum. There was a tendency (P = .0625) toward a decrease in ACE activity 45-120 minutes after enalapril administration, but ACE activity suppression was never > 16%. There was a tendency (P = .0625) toward a decrease in mean arterial pressure (MAP) 6-8 hours after enalapril administration. Serum concentrations of potassium, creatinine, and BUN and digital venous blood gases and lactate concentrations did not change. In response to angiotensin I, there was a tendency (P = .0625) toward a decrease in the MAP response 4-24 hours after enalapril administration. Single-dose enalapril at 0.5 mg/kg PO did not demonstrate significant availability, pharmacodynamic effect, or substantial suppression of ACE activity.     

Effect of ERK1/2/c-Fos signal pathway on angiotensin-(1-7) inhibiting proliferation of rat glomerular mesangial cell strain induced by angiotensin Ⅱ

AIM: To investigate the effect of ERK1/2/c-Fos signal pathway during angiotensin-(1-7) inhibiting proliferation of rat glomerular mesangial cell strain (GMCS) induced by angiotensin Ⅱ. METHODS: Rat glomerular mesangial cells (GMC) were co-cultured with angiotensin Ⅱ and different doses of angiotensin-(1-7). The numbers of GMC were evaluated by crystal violet staining. The amounts of p-ERK1/2 and c-Fos expressions were detected by Western blotting. RESULTS: Angiotensin- (1-7) showed its inhibitory effects on GMC number increasing induced by angiotensin Ⅱ as well as the amounts of p-ERK1/2 and c-Fos expressions in a concentration dependent manner. CONCLUSION: ERK/c-Fos signal pathway is involved in the inhibitory effects of angiotensin-(1-7) on angiotensin Ⅱ -induced GMC proliferation.