Effects of benazepril on cardiac function,free oxygen radicals,sarcoplasmic reticulum Ca2+-ATPase following cardiac ischemia-reperfusion in spontaneously hypertensive rats

AIM: To investigate the effects of angiotensin converting enzyme inhibitor (ACEI), benazepril (B), on cardiac function , free oxygen radicals, sarcoplasmic reticulum(SR) Ca²⁺-ATPase following ischemia-reperfusion in sportaneously hypertensive rats (SHRs). METHODS: Thirty 10-week-old female SHRs were randomly assigned into two groups: group SHR was control; The animal in group SHR+B was given with 10 mg/kg of benazepril per day. Another 15 Wistar rats with the same age and sex were normal control (group Wistar). After 12 weeks of pretreatment, all rats in each group were subjected to 30 min of left anterior descending coronary artery occlusion and 30 min of reperfusion. Hemodynamic parameters, left heart-to-body weight ratio (LVW/BW), myocardial malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and SR Ca²⁺-ATPase activity were measured. RESULTS: Compared to group Wistar, the rats in group SHR had higher blood pressure, LVW/BW and myocardial MDA concentration, more serious left cardiac function injury and lower myocardial SOD activity and SR Ca²⁺-ATPase activity; group SHR+B had lower myocardial MDA concentration, higher myocardial SOD activity, but no difference in blood pressure, LVW/BW, the degree of left cardiac function injury and myocardial SR Ca²⁺-ATPase activity. CONCLUSION: Benazepril can attenuate ischemia-reperfusion-induced cardiac function injury by regression of left ventricular hypertrophy (LVH), improving SR Ca²⁺-ATPase activity and decreasing oxygen free radicals injury in SHRs.     

Expression of ERK and MKP-1 in vascular smooth muscle of spontaneously hypertensive rats with different ages

AIM: To investigate the expression of mitogen- activated protein kinase and mitogen-activated protein kinase phosphatase-1 in thoracic aorta smooth muscles of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) with different ages and the relationship between those and hypertension. METHODS: The caudal arterial pressure was measured by tail-cuff. Protein expression of p-ERK was detected by Western blotting, and MKP-1 mRNA in thoracic aorta smooth muscle was examined by RT-PCR. RESULTS: (1) The blood pressure of SHR was obviously higher than that of age-matched WKY (P<0.01), elevated with age (P<0.05) and became stable from 14-week-old. (2) The expression of p-ERK and MKP-1 in SHR was higher than that in WKY in 5-week-old rats, and the expression of p-ERK increased with age, while the expression of MKP-1 decreased with age (P<0.05). CONCLUSION: MKP-1 may play an important role in the development of hypertension in SHR. The decrease in the expression of MKP-1 that resulted in the activation of MAPK may induce vascular smooth muscle proliferation and hypertrophy.     

Effects of atorvastatin on myocardium expression of peroxisome proliferator-activated receptors in spontaneously hypertensive rats

AIM: To investigate the effects of atorvastatin on myocardium peroxisome proliferator-activated receptors (PPARs) expression, regression of left ventricular hypertrophy, and the possible mechanisms in spontaneously hypertensive rats (SHR). METHODS: 16 nine-week-old male spontaneously hypertensive rats were randomly divided into two groups: SHR received atorvastatin at dose of 30 mg·kg-1·d-1 by oral gavage once daily for 8 weeks (SHR-A, n=8), and SHR received vehicle (0.9% saline) as controls (SHR, n=8). Age-matched Wistar-kyoto rats received vehicle for 8 weeks were served as normaltensive controls (WKY, n=8). Systolic blood pressure was measured at the beginning, 2, 4 and 8 weeks of the experiment. At the end of the experiment, plasma lipid levels were measured. Left ventricular hypertrophy was accessed by pathological analysis. The expressions of PPARα and PPARγ were investigated by the method of Western blotting. RESULTS: There was not much difference of systolic blood pressure and plasma lipid levels between SHR-A and SHR group (P>0.05). Compared with SHR group, left ventricular weight mass index decreased significantly in SHR-A group (P<0.01). The myocardium PPARα and PPARγ expression increased significantly (P<0.01). CONCLUSION: Atorvastatin regresses left ventricular hypertrophy and increases myocardium PPARα and PPARγ expression in spontaneously hypertensive rats, which is independent of its lipid-lowering activity.     

Up-regulation of miR-133a expression attenuates myocardial fibrosis in spontaneously hypertensive rats

AIM: To investigate the effect of up-regulated expression of microRNA-133a (miR-133a) on myocardial fibrosis in spontaneously hypertensive rats (SHR). METHODS: Wistar-Kyoto (WKY) rats with homologous normal blood pressure served as the normal control group. SHR were divided into SHR group, SHR+ adeno-associated virus (AAV) group and SHR+miR-133a-AAV group randomly. miR-133a carried by miR-133a-AAV was transfected into SHR heart by coronary perfusion. The rat tail artery pressure was monitored. The myocardial collagen deposition was observed by Masson staining. The expression of miR-133a in myocardial tissue was detected by real-time PCR. The protein levels of transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) were determined by immunohistochemistry and Western blot. RESULTS: Compared with the WKY rats, the tail artery pressure of the SHR increased significantly. The expression of miR-133a in heart decreased, and the expression levels of TGF-β1 and CTGF increased (P<0.05), and myocardial fibrosis occurred. After up-regulating the expression level of miR-133a in the heart of SHR, the myocardial fibrosis was significantly reduced, and the expression levels of TGF-β1 and CTGF decreased (P<0.05). CONCLUSION: Up-regulation of the miR-133a expression improves myocardial fibrosis induced by hypertension, which may be related to inhibiting the protein expression of TGF-β1 and CTGF in myocardium.     

Correlation between the effect of angiotensin-(1-7) on cardiac hypertrophy and extracellular signal-regulated kinase in pressure-overloaded rats

AIM: To investigate the effects and mechanisms of angiotensin-(1-7) on cardiac hypertrophy in pressure-overloaded rats. METHODS: Ar at model of pressure-overloaded heart was induced by constriction of abdominal aorta. Seventy-five male Sprague Dawley rats were randomized to sham-operated group, model control group and angiotensin-(1-7) treatment group. They were treated with intravenous infusion of angiotensin-(1-7) (25 microgram/kg per hour) or saline by minipump. RESULTS: Abdominal aortic banding resulted in a significant increases in LVW/BW, myocardial angiotensinⅡlevels, and p-ERK1/2 expression. Angiotensin-(1-7) had no effect on aortic banding-induced increases in myocardial angiotensinⅡlevels, but it significantly attenuated aortic banding-induced increases in LVW/BW and p-ERK1/2 expression. CONCLUSION: Angiotensin-(1-7) attenuates the development of cardiac hypertrophy in pressure-overloaded rats. It may be associated with the inhibition of p-ERK1/2 expression in cardiac tissue.     

Effects of irbesartan and perindopril on the myocardial expression of connexin 43, desmin and cardiac troponin T in rat cardiac hypertrophy induced by pressure overload

AIM: To investigate the effects of angiotensinⅡ receptor type Ⅰ antagonist irbesartan and angiotensin-converting enzyme inhibitor perindopril on the myocardial expression of connexin 43 (CX43), desmin and cardiac troponin T (cTnT) in the pressure overload-induced rat cardiac hypertrophy. METHODS: 40 male adult Sprague-Dawley rats were divided into 5 groups (8 animals for each): sham operation group and other four groups with ventricular hypertrophy caused by banding aortic artery. Drugs were given one week after operation as follows: sham operation group, normal saline (2 mL·kg-1·d-1 ig) was given; Operative groups: animals with ventricular hypertrophy were treated with normal saline 2 mL·kg-1·d-1 ig; Treatment groups: animals with ventricular hypertrophy were treated with perindopril 2 mg·kg-1·d-1 ig, irbesartan 20 mg·kg-1·d-1 ig or irbesartan 20 mg·kg-1·d-1 ig plus perindopril 2 mg·kg-1·d-1 ig, respectively. Left ventricular mass index (LVMI), transverse diameter of myocardial cell (TDM), and myocardial expression of CX43, desmin and cTnT by immunohistochemistry were performed at the end of 8 weeks of drug intervention. RESULTS: LVMI, TDM were remarkably decreased after drug intervention, compared to animals of operative group (P<0.05). Left ventricular hypertrophy induced by aortic banding in rats were associated with marked disorganization of gap junction distribution. In hypertrophied myocytes, CX43 immunolabeling was dispersed over the entire cell surface rather than confined to the intercalated disks. The CX43 were mainly distributed in the intercalated disks in irbesartan group, perindopril group and their combined group. The myocardial expression of CX43, desmin and cTnT in the operative group was lower than that in irbesartan group, perindopril group and their combined group (P<0.05). CONCLUSION: These data indicate that irbesartan and perindopril play beneficial roles in the myocardial CX43, desmin and cTnT expression and their distribution, and the restoration of myocardial cell structure and gap junction in pressure-overload myocardium hypertrophy.     

Change of Gq-phosphoinositide signaling pathway in left ventricular tissue in rats with chronic heart failure and reverse effect of benazepril on it

AIM: To investigate the changes of Gq-phosphoinositide pathway in left ventricular tissue of rats with chronic heart failure in order to assess the role of this signal pathway in the formation of heart failure. METHODS: Male Sprague-Dawle rats were divided into three groups: control, chronic heart failure and benazepril therapy group. Chronic heart failure was induced with adriamycin. Rats in benazepril group received benazepril 10 mg·kg-1·d-1 and adriamycin at the same time. Hemodynamic measurement was carried out after 4 weeks. The expression of Gα q/11 protein in left ventricle was detected by Western blotting analysis and activity of phospholipase C was measured by the method of hydrolysis of nuclear substrate. RESULTS: Compared with control group, the ±dp/dtmax in chronic heart failure group significantly decreased, and protein Gα q/11 expression, basic and stimulated phospholipase C activity significantly increased (P<0.01). The ±dp/dtmax in benazepril group was significantly lower than that in control but obviously higher than that in chronic heart failure group (P<0.05). Gα q/11 expression, basic and stimulated phospholipase C activity in benazepril group were significantly higher than those in control but obviously lower than those in heart failure group (P<0.01). CONCLUSION: Gq-phosphoinositide signaling pathway may play a role in the formation of chronic heart failure. Benazepril partialy attenuates the activation of phosphoinositide signaling pathway.     

Long-term insulin treatment improves postischemic cardiac structure and function via increasing serum BNP levels

AIM：To investigate the influence of long-term insulin treatment on postischemic cardiac structural and functional changes, and to further explore the underlying mechanisms. METHODS：Adult male SD rats were randomly divided into 4 groups (8~10 rats per group): sham group, myocardial infarction (MI) + saline (1 mL·kg-1·d-1, hypodermic injection for 4 weeks) group, MI + insulin (2 U·kg-1·d-1, hypodermic injection for 4 weeks) group and MI + insulin (2 U·kg-1·d-1, hypodermic injection for 4 weeks) + wortmannin ［a phosphatidylinositol 3-kinase (PI3K) inhibitor; 15 μg·kg-1·d-1, intraperitoneal injection 15 min before each insulin treatment］ group. The rats in the latter 3 groups were subject to ligation of the left anterior descending coronary artery, while those in sham group underwent the same surgical procedures without tying the sutures. The cardiac structural and functional changes were observed by echocardiogram, heart catheterization and microscopy with HE and Masson trichrome staining. Blood glucose was determined by Roche blood glucose meter, and the serum levels of insulin and brain natriuretic peptide (BNP) were detected by ELISA. The protein expression and phosphorylation of PI3K, Akt, glycogen synthase kinase 3β (GSK3β) and p38 mitogen-activated protein kinase (p38 MAPK) in myocardial tissues were detected by Western blotting. The mRNA expression of BNP, β-myosin heavy chain (β-MHC) and atrial natriuretic peptide (ANP) in myocardial tissues was determined by real-time fluorescence quantitative PCR. RESULTS：At the end of the 4th week, MI rats receiving long-term insulin treatment showed decreased ratio of heart length/heart weight, smaller systolic left ventricle cavity, thicker systolic interventricular septum, and increased cardiac ejection fraction, left ventricular development pressure and instantaneous first derivate of left ventricle pressure (P<0.05 vs MI + saline group). Moreover, insulin treatment significantly increased the phosphorylation of PI3K and Akt and the serum level of BNP, and inhibited the phosphorylation of p38 MAPK (P<0.05 vs MI + saline group), but did not change the mRNA expression of BNP in myocardial tissues. The effects of insulin on BNP were not blocked by wortmannin (P>0.05 vs MI + insulin group). CONCLUSION：Insulin improves postischemic cardiac structure and function by increasing serum BNP levels possibly independent of PI3K-Akt signaling pathway.     

Effect of moxonidine hydrochloride on left ventricular hypertrophy in spontaneously hypertensive rats

AIM:To investate the effect of domestric moxonidine hydrochloride on myocardium fibrosis and coronary artery microvascular structure in left ventricular hypertrophy of spontaneously hypertensive rats(SHR).METHODS:30 male SHR, aged 20 weeks, were divided into group Mox+SHR, Cap+SHR and SHR randomly (10 in each group). 10 age and sex-mached sprauge-dawley rats were designed as normal control(NC). At the end of 13 weeks, left ventricular wight/body weight ratio(LVW/BW), collagen volume fraction(CVF) and standardized perivascular collagen area(PVCA) as well as intramyocardial arterial average medial thickness (AMT) were determined.RESULTS:LVW/BW, CVF, PVCA and AMT in group Mox+SHR were lower significantly than that in group SHR, respectively.CONCLUSION:Long-term antihypertensive treatment with moxonidine hydrochloride reduces myocardium fibrosis and improves impaired coronary artery microvascular structure in left ventricular hypertrophy.     

Effect of atorvastatin on blood pressure in spontaneously hypertensive rats

AIM: To explore the mechanisms underlying the effect of atorvastatin on blood pressure in spontaneously hypertensive rats (SHR). METHODS: The effects of atorvastatin on plasma endothelin-1, aortic nitric oxide synthase, aortic smooth muscle cell (ASMC) apoptosis and p27 expression in SHR were evaluated. 12 eight-week-old SHR were randomized into atorvastatin group (ATV, n=6) and SHR group (n=6). 6 age-matched normotensive Wistar-Kyoto rats (WKY) were served as controls. 50 mg·kg-1·d-1 of atorvastatin was administered to ATV by gavage for 10 weeks. Serum cholesterol and triglycerides were measured, and systolic blood pressure of caudal artery was examined. Plasma endothelin-1 and nitric oxide synthase activity of aortic tissue were measured. ASMC apoptosis rate was detected by TUNEL technique, and positive expression rate of P27 in ASMC was analyzed. RESULTS: After 10 weeks, systolic blood pressure in ATV was significantly lower than that in SHR ［(134.17±3.60）mmHg vs （173.33±3.78）mmHg, P<0.01］. Compared with SHR, serum cholesterol and triglycerides were significantly lower (P<0.01, P<0.01) in ATV. Additionally，atorvastatin significantly decreased plasma endothelin-1 ［(130.04±40.07）ng/L vs （196.74±59.69）ng/L, P<0.05］ and increased nitric oxide synthase activity in aortic tissue ［(0.189±0.040）kU/g protein vs (0.124±0.057)kU/g protein, P<0.01］, compared with SHR. ASMC apoptosis rate was higher in ATV than that in SHR (16.94%±3.08% vs 9.01%±2.36%, P<0.01). Compared with WKY, positive expression rate of p27 in ASMC from ATV was higher (33.02%±5.01% vs 24.25%±4.41%, P<0.05), whereas that was lower in SHR (16.08%±7.09% vs 24.25%±4.41%, P<0.01). CONCLUSION: Atorvastatin may reduce the plasma endothelin-1， up-regulate nitric oxide synthase activity and ASMC P27 expression and facilitate ASMC apoptosis，which may effectively reduce blood pressure in 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.     

Expression of short-chain acyl-CoA dehydrogenase during heart development in rats and relationship with cardiac hypertrophy

AIM： To investigate the expression of short-chain acyl-CoA dehydrogenase during the heart deve-lopment in rats and to analyze the relationship between short-chain acyl-CoA dehydrogenase and cardiac hypertrophy in spontaneously hypertensive rats (SHR). METHODS：The expression and activity of short-chain acyl-CoA dehydrogenase in the hearts of Wistar rats with different ages were measured. Free fatty acids in serum and cardiac muscles were also determined. RESULTS：Compared with the fetal rats of 19 d, the expression and activity of short-chain acyl-CoA dehydrogenase in the postnatal rats of 1 d, 2 weeks, 6 weeks and 16 weeks were increased, and free fatty acids in the serum and myocardium were obviously decreased. The difference began in evidence from the age of 2 weeks. The expression of short-chain acyl-CoA dehydrogenase was significantly up-regulated with negative correlation to free fatty acids in the serum and myocardium during heart development. Systolic blood pressure was similar in 2-week-old SHR and WKY rats, which significantly increased in SHR of 6 weeks and 16 weeks old compared with the age-matched WKY rats. The ratio of left ventricular weight to body weight was markedly elevated in SHR of 2 weeks, 6 weeks and 16 weeks old compared with the age-matched WKY rats, indicating that the appearance of cardiac hypertrophy occurred before the development of hypertension in SHR. Compared with the age-matched WKY rats, the expression and activity of short-chain acyl-CoA dehydrogenase were decreased and free fatty acids in the serum and myocardium were obviously higher in SHR. The expression of short-chain acyl-CoA dehydrogenase was significantly down-regulated with a negative correlation to free fatty acids in the serum and myocardium of SHR. CONCLUSION：The expression of short-chain acyl-CoA dehydrogenase is increased during the heart development, which may be associated with the increase in cardiac fatty acid utilization. The down-regulated expression of short-chain acyl-CoA dehydrogenase in the hypertrophic heart may be responsible for the recapitulation of fetal energy metabolism.     

Relationship of microRNA-133a and TGF-β1 protein in myocardial tissues of spontaneously hypertensive rats

AIM：To observe the changes of microRNA-133a and transforming growth factor β1 (TGF-β1) protein in the myocardium of spontaneously hypertensive rats (SHR). METHODS：Male SHR (18 weeks old, n=12) and male Wistar-Kyoto rats (WKY, 18 weeks old, n=12) served as SHR group and control group, respectively. Caudal arterial blood pressure was detected by a noninvasive blood pressure measurement and analysis system. Myocardial collagen volume fraction (CVF) and perivascular collagen area ratio (PVCA) were determined by Masson staining. The level of miR-133a in the heart was detected by real-time quantitative PCR. The protein level of TGF-β1 in the heart was also analyzed by the methods of immunohistochemisty and Western blotting. RESULTS：Compared with control group, systolic and diastolic blood pressure, CVF and PVCA significantly increased, the expression of TGF-β1 protein was significantly up-regulated, and the level of miR-133a was significantly reduced in SHR group. In SHR group, the expression of miR-133a was decreased to (23.9±4.6)% in control group. A negative correlation between the levels of miR-133a and TGF-β1 protein in SHR group was observed (r=-0.791, P<0.01). CONCLUSION：The level of miR-133a is down-regulated along with the up-regulation of TGF-β1 protein expression and collagen synthesis in the myocardial tissues of SHR. miR-133a and TGF-β1 may be involved in myocardial fibrosis in SHR.     

Role of calcineurin in cTnI Asp128Tyr mutation-induced myocardial hypertrophy

AIM：To investigate the role of calcineurin (CaN) signaling pathway in myocardial hypertrophy induced by cardiac troponin I (cTnI) Asp128Tyr mutation. METHODS：The adenovirus containing cTnI Asp128Tyr mutation was transfected into the cultured neonatal rat cardiomyocytes. Cardiac hypertrophy was evaluated by determining the mRNA expression of atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) in the transfected cells. The effects of CaN inhibitors cyclosporine A (CsA) and FK506 on cardiac hypertrophy were also observed. The mRNA expression of ANF, BNP and CaN was measured by real-time quantitative PCR. The activity of CaN was also detected. RESULTS：Compared with blank control group, negative control virus group or virus containing wildtype cTnI gene group, the mRNA expression of ANF and BNP in mutation group (transfected with the adenovirus containing cTnI Asp128Tyr mutation) significantly increased, and decreased after treatment with CsA or FK506. The mRNA expression and activity of CaN increased in the mutation group compared with blank control group, negative control virus group or virus containing wild-type cTnI gene group. At the same time, the mRNA expression and the activity of CaN decreased after treatment with CsA or FK506. CONCLUSION：Calcineurin signaling pathway is involved in the cardiac hypertrophy induced by cTnI Asp128Tyr mutation.     

The renal L-arginine/nitric oxide pathway and erythrocyte L-arginine transport in spontaneously hypertensive rats

AIM: To investigate the changes of the renal L-arginine /nitric oxide pathway and the relationship of L-arginine transport between kidney and erythrocytes in spontaneously hypertensive rat (SHR). METHODS: Sixteen week old SHR, 16 week old SHR with captopril (CAP) treated for four weeks and 16 week old WKY rats were used in the experiment. L-arginine transport, NO synthase(NOS) activity, nitrite and cyclic GMP (cGMP) content were measured in renal tissue or erythrocytes. RESULTS: In the renal tissue, compared with that of WKY group, the Vmax of high-or low-affinity L-arginine transporter, NOS activity, NO₂^- and cGMP content of SHR group were significantly decreased (P＜0.01 or P＜0.05). The Vmax of high-affinity L-arginine transporter and NOS activity of CAP group were significantly enhanced as compared with SHR group (+90%, P＜0.01; +58.6%, P＜0.05). The NOS activity had significant positive correlation with the Vmax of high-affinity L-arginine transporter (r=0.585, P＜0.05). The changes of erythrocyte L-arginine transport were the same as that of kidney. The Vmax of SHR group was lower than that of WKY group (-30%, P＜0.01), and the Vmax of CAP group was higher than that of SHR group (+26.5%, P＜0.01). Km was not significantly changed. There is a positive correlation between the Vmax of L-arginine transport in erythrocyte and the Vmax of high- or low-affinity L-arginine transporter in renal tissue, (r=0.8434, P＜0.01, high-affinity; r=0.5255, P＜0.05, low-affinity). CONCLUSION: There existed a functional inhibition in L-arginine/nitric oxide pathway in the kidney of SHR. It can be recovered obviously by captopril treatment. The changes of L-arginine transport in kidney coincide with that in erythrocyte.     

Protective effects of total saponins of panax notoginseng on myocardial hypertrophy and fibrosis induced by isoproterenol in rats

AIM: To investigate the protective effects of total saponins of panax notoginseng (PNS) on myocardial hypertrophy and fibrosis induced by isoproterenol (ISO) in rats.METHODS: Myocardial hypertrophy and fibrosis model of rats were induced by injection of ISO (5 mg·kg^-1·d^-1,sc) for 7 days.From day 2,the rats were administered with PNS at dose of 25 and 50 mg·kg^-1·d^-1,ip for 14 days,the control and ISO model group were received saline injection.Then,the heart-weight (HW),left ventricular weight (LVW),the ratio of HW/BW and LVW/BW (LVI) were measured;the hydroxyproline and malondialdehyde (MDA) and angiotensin (AngII) content of left ventricle.The level of nitric oxide (NO),nitric oxide synthase (NOS),superoxide disrnutase (SOD) and glutathione peroxidase (GSH-Px) activities in left ventricle were determined by spectrophotemetry and radioimmunoassay,respectively.RESULTS: Compared with NS control group,the ratio of HW/BW,LVW/BW and the content of hydroxyproline,AngII,MDA and iNOS activity in the left ventricle were significantly increased.The cNOS,SOD,GSH-Px activities and NO content were obriously decreased in the ISO model group.After treatment with PNS,the left ventricular NO content,cNOS,SOD and GSH-Px activities were markedly higher than those in ISO model group.The content of MDA,AngII and iNOS activities and the ratio of HW/BW,LVI were significantly lower than those in ISO model group.CONCLUSION: PNS reverses the myocardial hypertrophy and fibrosis induced by isoproterenol in rats.This effect may be related to eliminating the oxygen free radicals and raising NO level.     

Effects of valsartan alone or in combination with benazepril on blood pressure and left ventricular hypertrophy in spontaneously hypertensive rats

AIM:To evaluate the effects of different doses of valsartan alone or with concomitant be-nazepril on blood pressure,left ventricular hypertrophy,RAASfunction and endoxi nlevel in spontaneously hy-pertensive rats(SHR).METHODS:Thirty SHR(fourteen-week-old,male)were divi ded into five groups(six rats in each group):SHR control group:fed with normal saline;benazepril group:fed with 1 mg·kg^-1·d^-1benazepril);low dose valsartan group:fed with 8 mg·kg^-1·d^-1valsartan;high dose valsartan group:fed with 24 mg·kg^-1·d^-1valsartan;combination drug therapy group:fed with valsartan(8 mg·kg^-1·d^-1)and benazepril(1 mg·kg^-1·d^-1),all for 8 weeks.WKY control group(n=6):fed with normal saline for 8 weeks.RESULTS:SBP,LVM/BW,TDMof SHR were remarkably lower than those of control after drug i n-tervene,and effect on SBP was most remarkable in high dose valsartan group and i nthe combi nation drug ther-apy group;effect on LVM/BW,TDM were most remarkable in combination drug therapy group.Renin activi-ties in plasma and myocardiumwere remarkably i ncreased in drug i ntervene groups.The levels of AngⅡi nplasma and myocardiumwere remarkably increased in two different dose of valsartan treati ng group,and thelarger dose of valsartan were,the higher levels of AngⅡin plasma and myocardium were;decreased in be-nazepril treati ng group and combination drug therapy group.Na⁺-K⁺-ATPase activities in myocardi umwere remarkably i ncreased and the level of endoxi n i n myocardium were remarkably decreased as SBP de-creased after drug intervene.CONCLUSION:Different dose of valsartan alone or combi ned with benazeprilcan decrease SBP of SHR,have the effect of inhibiti ng progression of ventricular hypertrophy.The effect ofcombination drug therapy group was most remarkable among five groups and can avoi d the si de effect of highAngⅡin plasma and myocardiumduri ng long-termuse of valsartan alone.     

Functional changes of perivascular adipose tissue in hypertensive rats and the effects of statins therapy

AIM:To study the functional changes of perivascular adipose tissue (PVAT) in SHR and the effects of statins therapy.METHODS:Adult SHR at 10 weeks of age were treated with atorvastatin (50 mg·kg-1·d-1) or Xuezhikang (2 400 mg·kg-1·d-1) for 16 weeks.Age-matched untreated SHR and WKY were used as controls.Tail-cuff systolic blood pressure (SBP) was measured at the beginning and the end of experiment.Thoracic aorta was divided into two segments: vessel without PVAT ［Fat (-)］ and vessel with PVAT ［Fat (+)］.The differences in contractile force induced by phenylephrine in these vessels from the four groups of rats were compared.RESULTS:SBP in SHR was significantly higher than that in WKY at the beginning of the experiment.SBP of SHR treated with statins and WKY control did not show statistical difference during the treatment period.Contractile force of Fat(+) vessels in WKY and SHR groups treated with statins was lower than that in Fat(-) vessels.There was no difference in the contractile force between Fat(+) and Fat(-) vessels in SHR control.Bathing solution transferred from Fat(+) vessels in WKY,SHR-A,and SHR-X caused a relaxation response in Fat (-) vessels,but not in control SHR.CONCLUSIONS:PVAT in WKY released a transferable relaxation factor which attenuated the responsiveness of the vessels to phenylephrine.The release or the action of this relaxation factor was reduced in the SHR.Treatment with statins restored the release or the action of this relaxation factor in the SHR.