Angiotensin-(1–7) stimulates high atrial pacing-induced ANP secretion via Mas/PI3-kinase/Akt axis and Na+/H+ exchanger

2010 ◽  
Vol 298 (5) ◽  
pp. H1365-H1374 ◽  
Author(s):  
Amin Shah ◽  
Rukhsana Gul ◽  
Kuichang Yuan ◽  
Shan Gao ◽  
Young-Bin Oh ◽  
...  

Angiotensin-(1–7) [ANG-(1–7)], one of the bioactive peptides produced in the renin-angiotensin system, plays a pivotal role in cardiovascular physiology by providing a counterbalance to the function of ANG II. Recently, it has been considered as a potential candidate for therapeutic use in the treatment of various types of cardiovascular diseases. The aim of the present study is to explain the modulatory role of ANG-(1–7) in atrial natriuretic peptide (ANP) secretion and investigate the functional relationship between two peptides to induce cardiovascular effects using isolated perfused beating rat atria and a cardiac hypertrophied rat model. ANG-(1–7) (0.01, 0.1, and 1 μM) increased ANP secretion and ANP concentration in a dose-dependent manner at high atrial pacing (6.0 Hz) with increased cGMP production. However, at low atrial pacing (1.2 Hz), ANG-(1–7) did not cause changes in atrial parameters. Pretreatment with an antagonist of the Mas receptor or with inhibitors of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), or nitric oxide synthase blocked the augmentation of high atrial pacing-induced ANP secretion by ANG-(1–7). A similar result was observed with the inhibition of the Na+/H+ exchanger-1 and Ca2+/calmodulin-dependent kinase II (CaMKII). ANG-(1–7) did not show basal intracellular Ca2+ signaling in quiescent atrial myocytes. In an in vivo study using an isoproterenol-induced cardiac hypertrophy animal model, an acute infusion of ANG-(1–7) increased the plasma concentration of ANP by twofold without changes in blood pressure and heart rate. A chronic administration of ANG-(1–7) increased the plasma ANP level and attenuated isoproterenol-induced cardiac hypertrophy. The antihypertrophic effect was abrogated by a cotreatment with the natriuretic peptide receptor-A antagonist. These results suggest that 1) ANG-(1–7) increased ANP secretion at high atrial pacing via the Mas/PI3K/Akt pathway and the activation of Na+/H+ exchanger-1 and CaMKII and 2) ANG-(1–7) decreased cardiac hypertrophy which might be mediated by ANP.

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Yasuhide Kuwabara ◽  
Takahiro Horie ◽  
Osamu Baba ◽  
Toru Kita ◽  
Takeshi Kimura ◽  
...  

Rationale: In some type 2 diabetes mellitus (T2D) patients without hypertension, cardiac hypertrophy and attenuated cardiac function are observed, and this insult is termed “diabetic cardiomyopathy.” Tons of evidence suggests that microRNAs are involved in cardiac diseases. However, the functions of microRNAs in the diabetic cardiomyopathy induced by T2D and obesity are not fully understood. Methods and Results: C57BL/6 mice were fed a high-fat diet (HFD) for 20 weeks, which induced obesity and T2D. MicroRNA microarray and real-time PCR revealed that miR-451 levels were significantly increased in the T2D mouse hearts (n=4-5, p<0.05). Because excess supply of saturated fatty acids is a cause of diabetic cardiomyopathy, we stimulated neonatal rat cardiac myocytes (NRCMs) with palmitate in physiological albumin concentration and confirmed that miR-451 expression was increased in a dose-dependent manner (n=6-12, p<0.01). Loss of miR-451 function ameliorated palmitate-induced lipotoxicity in NRCMs (n=4, p<0.05). Calcium-binding protein 39 (Cab39) is a scaffold protein of liver kinase B1 (LKB1), an upstream kinase of AMP-activated protein kinase (AMPK). Cab39 was a direct target of miR-451 in NRCMs and Cab39 overexpression rescued the palmitate-induced lipotoxicity in NRCMs (n=4, p<0.01). To clarify miR-451 functions in vivo, we generated cardiomyocyte-specific miR-451 knockout (cKO) mice. HFD-induced cardiac hypertrophy and contractile reserves were ameliorated in cKO mice compared with HFD-fed control mice. Protein levels of Cab39 and phosphorylated AMPK were increased and phosphorylated mammalian target of rapamycin (mTOR) was reduced in HFD-fed cKO mouse hearts compared with HFD-fed control mouse hearts (n=10-12, p<0.05). We also measured the lipotoxic intermediates, triglyceride and ceramide, in these mouse hearts using HPLC-evaporative light scattering detector (ELSD). Although there was no difference in triglyceride levels (n=3-5), ceramide level was decreased in HFD-fed cKO mice compared with HFD-fed control mice (n=3-5, p<0.05). Conclusions: Our results indicate that miR-451 exacerbates diabetic cardiomyopathy. miR-451 is a potential therapeutic target for cardiac disease caused by T2D and obesity.


Author(s):  
Li Lin ◽  
Wei Xu ◽  
Yongqing Li ◽  
Ping Zhu ◽  
Wuzhou Yuan ◽  
...  

Wnt/β-catenin signalling plays a key role in pathological cardiac remodelling in adults. The identification of a tissue-specific Wnt/β-catenin interaction factor may realise a tissue-specific clinical targeting strategy. Drosophila Pygo codes for the core interaction factor of Wnt/β-catenin. Two Pygo homologs, Pygo1 and Pygo2, have been identified in mammals. Different from the ubiquitous expression profile of Pygo2, Pygo1is enriched in cardiac tissue. However, the role of Pygo1 in mammalian cardiac disease remains unelucidated. Here, we found that Pygo1 was upregulated in human cardiac tissues with pathological hypertrophy. Cardiac-specific overexpression of Pygo1 in mice spontaneously led to cardiac hypertrophy accompanied by declined cardiac function, increased heart weight/body weight and heart weight/tibial length ratios and increased cell size. The canonical β-catenin/T-cell transcription factor 4 complex was abundant in Pygo1-overexpressingtransgenic(Pygo1-TG) cardiac tissue,and the downstream genes of Wnt signaling, i.e., Axin2, Ephb3, and C-myc, were upregulated. A tail vein injection of β-catenin inhibitor effectively rescued the phenotype of cardiac failure and pathological myocardial remodelling in Pygo1-TG mice. Furthermore, in vivo downregulated pygo1 during cardiac hypertrophic condition antagonized agonist-induced cardiac hypertrophy. Therefore, our study is the first to present in vivo evidence demonstrating that Pygo1 regulates pathological cardiac hypertrophy in a canonical Wnt/β-catenin-dependent manner, which may provide new clues for a tissue-specific clinical treatment targeting this pathway.


Author(s):  
MAHESWARI REDDY B ◽  
DHANAPAL CK ◽  
LAKSHMI BVS

Objective: The current study evaluates anti-Parkinson’s activity of aqueous extracts of leaves of Murraya koenigii (MK) (AEMK) against paraquat (PQ)-induced Parkinsonism in rats. Methods: In this study, effects of MK (100, 200, and 400 mg/kg, p.o.) were studied using in vivo behavioral parameters such as catalepsy, muscle rigidity, and locomotor activity and its effects on neurochemical parameters malondialdehyde, catalase (CAT), glutathione (GSH) reductase, GSH peroxidase, and GSH in rats. Results: Parkinson’s disease was induced by administering PQ 10 mg/kg b.w/i.p once in a week for 4 weeks. The increased cataleptic scores were significantly (p<0.001) found to be reduced, with the AEMK in a dose-dependent manner. Chronic administration of PQ significantly induced motor dysfunction (muscle rigidity and hypolocomotion), showed a significant increase in lipid peroxidation level, and depleted the levels of GSH, CAT, and reduced GSH. Daily administration of AEMK significantly improved motor performance and also significantly attenuated oxidative damage. Conclusion: The study proved that MK treatment significantly attenuated motor defects and also protected the brain from oxidative stress.


2000 ◽  
Vol 278 (1) ◽  
pp. H208-H221 ◽  
Author(s):  
Sook Jeong Lee ◽  
Sung Zoo Kim ◽  
Xun Cui ◽  
Suhn Hee Kim ◽  
Kyung Sun Lee ◽  
...  

The purpose of the present experiments was to define the role of C-type natriuretic peptide (CNP) in the regulation of atrial secretion of atrial natriuretic peptide (ANP) and atrial stroke volume. Experiments were performed in perfused beating and nonbeating quiescent atria, single atrial myocytes, and atrial membranes. CNP suppressed in a dose-related fashion the increase in atrial stroke volume and ANP secretion induced by atrial pacing. CNP caused a right shift in the positive relationships between changes in the secretion of ANP and atrial stroke volume or translocation of the extracellular fluid (ECF), which indicates the suppression of atrial myocytic release of ANP into the paracellular space. The effects of CNP on the secretion and contraction were mimicked by 8-bromoguanosine 3′,5′-cyclic monophosphate (8-BrcGMP). CNP increased cGMP production in the perfused atria, and the effects of CNP on the secretion of ANP and atrial dynamics were accentuated by pretreatment with an inhibitor of cGMP phosphodiesterase, zaprinast. An inhibitor of the biological natriuretic peptide receptor (NPR), HS-142-1, attenuated the effects of CNP. The suppression of ANP secretion by CNP and 8-BrcGMP was abolished by a depletion of extracellular Ca2+ in nonbeating atria. Natriuretic peptides increased cGMP production in atrial membranes with a rank order of potency of CNP > BNP > ANP, and the effect was inhibited by HS-142-1. CNP and 8-BrcGMP increased intracellular Ca2+ concentration transients in single atrial myocytes, and mRNAs for CNP and NPR-B were expressed in the rabbit atrium. From these results we conclude that atrial ANP release and stroke volume are controlled by CNP via NPR-B-cGMP mediated signaling, which may in turn act via regulation of intracellular Ca2+.


1996 ◽  
Vol 271 (6) ◽  
pp. H2197-H2208 ◽  
Author(s):  
J. Lai ◽  
H. Jin ◽  
R. Yang ◽  
J. Winer ◽  
W. Li ◽  
...  

Several prostaglandins [prostaglandin (PG) A2, -B2, -D2, -E2, -F2 alpha, and -I2 and carbaprostacyclin] and the thromboxane analogue U-46619 were analyzed for the ability to induce hypertrophy of rat neonatal cardiac ventricular myocytes. Myocyte hypertrophy was induced specifically by PGF2 alpha. Myocytes exposed to this prostanoid in culture increased in size and protein content. The contractile fibrils within the cells became organized into parallel arrays, and the cells tended to cluster and beat spontaneously. PGF2 alpha also induced the expression of c-fos, atrial natriuretic factor (ANF), and alpha-skeletal actin in these cells. The effects of PGF2 alpha were compared with several known cardiac myocyte hypertrophy factors (phenylephrine, endothelin-1, leukemia inhibitory factor, cardiotrophin-1, and angiotensin II). PGF2 alpha was found to be intermediate in potency among the factors but induced a level of ANF production that was approximately 10-fold higher than any of the other effectors. Responsiveness to PGF2 alpha was not limited to neonatal cardiocytes. Ventricular myocytes isolated from adult rats also responded specifically to PGF2 alpha with a morphological change similar to that observed with phenylephrine and by producing ANF. In rats, chronic administration of fluprostenol, a potent agonist analogue of PGF2 alpha, resulted in a dose-dependent increase in heart weight- and ventricular weight-to-body weight ratios. The amount of PGF2 alpha extractable from the hearts of rats with cardiac hypertrophy induced by myocardial infarction was also found to be greater than that in sham-operated control rats. These results indicate that PGF2 alpha may play an important role in inducing cardiac hypertrophy.


1998 ◽  
Vol 275 (5) ◽  
pp. H1826-H1833 ◽  
Author(s):  
L. G. Melo ◽  
A. T. Veress ◽  
U. Ackermann ◽  
H. Sonnenberg

Atrial natriuretic peptide (ANP) exerts a chronic hypotensive effect due to a decrease in total peripheral resistance (TPR). This study examines if chronic ANP-dependent vasodilation is attributable to differences in the cardiovascular regulatory activity of vascular endothelium (VE), based on evidence that ANP affects synthesis/release and target cardiovascular effects of endothelin-1 (ET-1), C-type natriuretic peptide (CNP), and nitric oxide (NO). To determine if the synthetic activity of resistance vasculature VE is chronically altered by plasma ANP activity, we measured ET-1, CNP, and endothelial constitutive NO synthase (ecNOS) concentration and total NOS enzyme activity in homogenates of kidney, heart, lung, hindquarter skeletal muscle, and brain from hypotensive transgenic mice with elevated plasma ANP, hypertensive knockout mice (−/−) characterized by the absence of ANP, and the corresponding normotensive wild-type (NT, +/+) mice. Tissue distribution and abundance patterns of ET-1, CNP, ecNOS, and NOS enzyme activity were comparable between the different genotypes and did not differ significantly between mutant and control mice. Antagonism of ETA/B receptors in −/− and +/+ mice in vivo with SB-209670 reduced arterial blood pressure (ABP) significantly and comparably in both genotypes (−27 ± 4 and −25 ± 2% change for −/− and +/+ mice, respectively) independent of any significant changes in heart rate (HR) (−6 ± 8 and −4 ± 4% change for −/− and +/+ mice, respectively). Immunoneutralization of CNP-specific guanylate cyclase-linked receptors (GC-B) with monoclonal antibodies (3G12) increased ABP slightly, but not significantly, by similar relative amounts in both −/− (10 ± 6% change) and +/+ mice (8 ± 3% change), without changing HR significantly (4 ± 1% change for both +/+ and −/− mice). Inhibition of NOS activity (by N G-nitro-l-arginine methyl ester) significantly increased ABP, but the changes were comparable between −/− (53 ± 5% change) and +/+ mice (50 ± 6% change) and occurred in the absence of significant changes in HR (−1 ± 5 and 7 ± 5% change for −/− and +/+ mice, respectively). We conclude that the differences in ABP associated with chronic variations in endogenous ANP activity are not due to alterations in synthesis or responsiveness of the cardiovascular system to the effects of ET-1, CNP, or NO.


1988 ◽  
Vol 74 (2) ◽  
pp. 207-211 ◽  
Author(s):  
A. Hughes ◽  
S. Thom ◽  
P. Goldberg ◽  
G. Martin ◽  
P. Sever

1. The effect of a α-human atrial natriuretic peptide (1–28) (ANP) on human vasculature was investigated in vivo and in vitro. Possible involvement of vascular dopamine receptors and the renin-angiotensin system in the response to ANP was also studied in vivo. 2. Forearm blood blow was measured by venous occlusion plethysmography. Isolated human blood vessels were studied using conventional organ bath techniques. 3. ANP (0.1–1 μg/min, intra-arterially) produced a dose-dependent increase in forearm blood flow, corresponding to a 163% increase in net forearm blood flow in the study arm. This action of ANP was not antagonized by (R)-sulpiride (100 μg/min, intra-arterially), a selective vascular dopamine receptor antagonist, or 50 mg of oral captopril, an inhibitor of angiotensin-converting enzyme. 4. ANP (1 nmol/l–1 μmol/l) produced concentration-dependent relaxation of isolated human arteries, including brachial artery, but was without effect on isolated human saphenous vein. 5. ANP produces vasodilatation in vivo and relaxes isolated human arterial smooth muscle. This action of ANP may contribute to its reported hypotensive effects in vivo.


Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 478 ◽  
Author(s):  
Rasha Al-Rikabi ◽  
Hanady Al-Shmgani ◽  
Yaser Hassan Dewir ◽  
Salah El-Hendawy

(1) Background: Plant flavonoids are efficient in preventing and treating various diseases. This study aimed to evaluate the ability of hesperidin, a flavonoid found in citrus fruits, in inhibiting lipopolysaccharide (LPS) induced inflammation, which induced lethal toxicity in vivo, and to evaluate its importance as an antitumor agent in breast cancer. The in vivo experiments revealed the protective effects of hesperidin against the negative LPS effects on the liver and spleen of male mice. (2) Methods: In the liver, the antioxidant activity was measured by estimating the concentration of glutathione (GSH) and catalase (CAT), whereas in spleen, the concentration of cytokines including IL-33 and TNF-α was measured. The in vitro experiments including MTT assay, clonogenity test, and sulforhodamine 101 stain with DAPI (4′, 6-diamidino-2-phenylindole) were used to assess the morphological apoptosis in breast cancer cells. (3) Results: The results of this study revealed a significant increase in the IL-33 and TNF-α cytokine levels in LPS challenged mice along with a considerable elevation in glutathione (GSH); moreover, the catalase (CAT) level was higher compared to that of the control group. Cytotoxicity of the MCF-7 cell line revealed significant differences among the groups treated with different concentrations when compared to the control groups, in a concentration-dependent manner. Hesperidin significantly inhibited the colony formation of MCF7 cells when compared to that of control. Clear changes were observed in the cell shape, including cell shrinkage and chromatin condensation, which were associated with a later apoptotic stage. (4) Conclusion: The results indicate that hesperidin might be a potential candidate in preventing diseases.


2010 ◽  
Vol 299 (2) ◽  
pp. H347-H355 ◽  
Author(s):  
Ji-Yoon Noh ◽  
Kyung-Min Lim ◽  
Ok-Nam Bae ◽  
Seung-Min Chung ◽  
Sang-Wook Lee ◽  
...  

Increased phosphatidic acid (PA) and phospholipase D (PLD) activity are frequently observed in various disease states including cancers, diabetes, sepsis, and thrombosis. Previously, PA has been regarded as just a precursor for lysophosphatidic acid (LPA) and diacylglycerol (DAG). However, increasing evidence has suggested independent biological activities of PA itself. In the present study, we demonstrated that PA can enhance thrombogenic activities in human erythrocytes through phosphatidylserine (PS) exposure in a Ca2+-dependent manner. In freshly isolated human erythrocytes, treatment of PA or PLD induced PS exposure. PA-induced PS exposure was not attenuated by inhibitors of phospholipase A2or phosphatidate phosphatase, which converts PA to LPA or DAG. An intracellular Ca2+increase and the resultant activation of Ca2+-dependent PKC-α appeared to underlie the PA-induced PS exposure through the activation of scramblase. A marginal decrease in flippase activity was also noted, contributing further to the maintenance of exposed PS on the outer membrane. PA-treated erythrocytes showed strong thrombogenic activities, as demonstrated by increased thrombin generation, endothelial cell adhesion, and erythrocyte aggregation. Importantly, these procoagulant activations by PA were confirmed in a rat in vivo venous thrombosis model, where PA significantly enhanced thrombus formation. In conclusion, these results suggest that PA can induce thrombogenic activities in erythrocytes through PS exposure, which can increase thrombus formation and ultimately contribute to the development of cardiovascular diseases.


2004 ◽  
Vol 287 (4) ◽  
pp. H1712-H1720 ◽  
Author(s):  
Yuehua Li ◽  
Tuanzhu Ha ◽  
Xiang Gao ◽  
Jim Kelley ◽  
David L. Williams ◽  
...  

In the present study, we examined whether NF-κB activation is required for cardiac hypertrophy in vivo. Cardiac hypertrophy in rats was induced by aortic banding for 1, 3, and 5 days and 1–6 wk, and age-matched sham-operated rats served as controls. In a separate group of rats, an IκB-α dominant negative mutant (IκB-αM), a superrepressor of NF-κB activation, or pyrrolidinedithiocarbamate (PDTC), an antioxidant that can inhibit NF-κB activation, was administered to aortic-banded rats for 3 wk. The heart weight-to-body weight ratio was significantly increased at 5 days after aortic banding, peaked at 4 wk, and remained elevated at 6 wk compared with age-matched sham controls. Atrial natriuretic peptide and brain natriuretic peptide mRNA expressions were significantly increased after 1 wk of aortic banding, reached a maximum between 2 and 3 wk, and remained increased at 6 wk compared with age-matched sham controls. NF-κB activity was significantly increased at 1 day, reached a peak at 3 wk, and remained elevated at 6 wk, and IKK-β activity was significantly increased at 1 day, peaked at 5 days, and then decreased but remained elevated at 6 wk after aortic banding compared with age-matched sham controls. Inhibiting NF-κB activation in vivo by cardiac transfection of IκB-αM or by PDTC treatment significantly attenuated the development of cardiac hypertrophy in vivo with a concomitant decrease in NF-κB activity. Our results suggest that NF-κB activation is required for the development of cardiac hypertrophy in vivo and that NF-κB could be an important target for inhibiting the development of cardiac hypertrophy in vivo.


Sign in / Sign up

Export Citation Format

Share Document