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Lee HS, Cho KW, Kim HY, Ahn YM. Chamber-specific regulation of atrial natriuretic peptide secretion in cardiac hypertrophy: atrial wall dynamics in the ANP secretion. Pflugers Arch 2020; 472:639-651. [DOI: 10.1007/s00424-020-02377-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 12/21/2022]
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Tan R, Ahn YM, Kim HY, Lee YJ, Cho KW, Kang DG, Lee HS. Atrial secretion of ANP is suppressed in renovascular hypertension: shifting of ANP secretion from atria to the left ventricle. Am J Physiol Heart Circ Physiol 2018; 315:H590-H601. [PMID: 29979625 DOI: 10.1152/ajpheart.00612.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present study, the change in secretion of atrial natriuretic peptide (ANP) from the atria was defined in hypertension accompanied by ventricular hypertrophy and increased synthesis of ANP. To identify the change of the secretion and mechanisms involved, experiments were performed in isolated perfused beating atria from sham-operated normotensive and renovascular hypertensive rats. Expression of ANP, natriuretic peptide receptor (NPR)-C, components of the renin-angiotensin system, and muscarinic signaling pathway was measured in cardiac tissues. Basal levels of ANP secretion and acetylcholine (ACh)- and stretch-induced activation of ANP secretion were suppressed in the atria from hypertensive compared with normotensive rats. ACh increased ANP secretion via M2 muscarinic ACh receptor-ACh-sensitive K+ channel signaling. In hypertensive rats, ANP concentration increased in the left ventricle but decreased in the right ventricle. The atrial concentration of ANP was not changed in hypertensive compared with normotensive rats. ANP mRNA expression was accentuated in the left ventricle but suppressed in the other cardiac chambers in the hearts of hypertensive rats. NPR-C expression was inversely related to ANP mRNA levels. Angiotensin II type 1 receptor (AT1R) expression was accentuated in the cardiac chambers from hypertensive rats compared with normotensive rats, whereas angiotensin II type 2 receptor, M2 muscarinic receptor, and Kir3.4 channels were suppressed. AT1R blockade with losartan reversed the change observed in hypertensive rats. The present findings indicate that renovascular hypertension shifts the major site of ANP secretion and synthesis from the atria to the left ventricle through modulation of the expression of ANP, NPR-C, AT1R, and the M2 muscarinic signaling pathway. NEW & NOTEWORTHY Renovascular hypertension suppresses the atrial secretion of ANP and shifts the major site of the regulation of ANP secretion and synthesis from atria to the hypertrophied left ventricle possibly via modulation of the expression of ANP, natriuretic peptide receptor-C, angiotensin II subtype 1 receptor, and M2 muscarinic signaling pathway.
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Affiliation(s)
- Rui Tan
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
| | - You Mee Ahn
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
| | - Hye Yoom Kim
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
| | - Yun Jung Lee
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
| | - Kyung Woo Cho
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
| | - Dae Gill Kang
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
| | - Ho Sub Lee
- Hanbang Cardio-Renal Syndrome Research Center, Department of Herbal Resources, Professional Graduate School of Oriental Medicine Wonkwang University, Iksan, Korea
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Han JH, Bai GY, Park JH, Yuan K, Park WH, Kim SZ, Kim SH. Regulation of stretch-activated ANP secretion by chloride channels. Peptides 2008; 29:613-21. [PMID: 18226426 DOI: 10.1016/j.peptides.2007.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2007] [Revised: 11/30/2007] [Accepted: 12/04/2007] [Indexed: 11/23/2022]
Abstract
This study was aimed to define roles of stretch-activated ion channels (SACs), especially Cl(-) channels, in regulation of atrial natriuretic peptide (ANP) secretion using isolated perfused beating atria. The volume load was achieved by elevating height of outflow catheter connected to isolated rat atria and the pressure load was achieved by decreasing diameter of outflow catheter. Both methods increased atrial contractility similarly although volume load was different (736microl for volume load vs. 129microl for pressure load). Atrial stretch by volume load markedly increased ECF translocation and ANP secretion but the pressure load slightly increased. The ANP secretion was positively correlated to workload generated by volume or pressure load. Treatment of atria with gadolinium, a blocker for SACs, attenuated the ECF translocation and the ANP secretion induced by volume load. A blocker for Ca2+-activated Cl(-) channel, niflumic acid (NFA), accentuated the ANP secretion induced by volume load whereas a blocker for swelling-activated Cl(-) channel, diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS), attenuated the ANP secretion. The ANP secretion of hypertrophied atria by volume load was markedly reduced and the augmented effect of NFA on volume load-induced ANP secretion was not observed. These results indicate that Cl(-) channels may differently regulate stretch-activated ANP secretion.
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Affiliation(s)
- Jeong Hee Han
- 2-20 Keum-Am-Dong-San, Department of Physiology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 561-180, Republic of Korea
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Wakisaka O, Takahashi N, Shinohara T, Ooie T, Nakagawa M, Yonemochi H, Hara M, Shimada T, Saikawa T, Yoshimatsu H. Hyperthermia treatment prevents angiotensin II-mediated atrial fibrosis and fibrillation via induction of heat-shock protein 72. J Mol Cell Cardiol 2007; 43:616-26. [PMID: 17884089 DOI: 10.1016/j.yjmcc.2007.08.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 07/19/2007] [Accepted: 08/02/2007] [Indexed: 12/01/2022]
Abstract
We tested the hypothesis that atrial fibrosis and atrial fibrillation (AF) evoked by angiotensin II (AII) could be prevented by the induction of heat-shock protein 72 (HSP72) by hyperthermia (HT). In cultured atrial fibroblasts isolated from male Sprague-Dawley rats, HT (42 degrees C) was applied for 30 min. AII (100 nmol/L) was added to the medium 8 h later. HT induced the expression of HSP72, which was associated with the attenuation of AII-induced extracellular signal-regulated kinase (ERK1/ERK2) phosphorylation, alpha-smooth muscle actin (alpha-SMA) expression, transforming growth factor-beta(1) secretion, collagen synthesis, and expression of collagen type I and tissue inhibitor of metalloproteinases-1. A small interfering RNA targeting HSP72 abolished these anti-fibrotic effects of HT. In male Sprague-Dawley rats in vivo, an osmotic mini-pump was subcutaneously implanted for continuous infusion of AII (400 ng/kg/min). Whole-body HT (43 degrees C, 20 min) was applied 24 h before and 7, 14, and 21 days after the start of the AII infusion. Repeated HT led to the induction of HSP72 expression, which resulted in an attenuation of AII-induced left atrial fibrosis. In an electrophysiological study using isolated perfused heart, continuous AII caused slowing of interatrial conduction without affecting atrial refractoriness. In AII-treated hearts, extrastimuli from the right atrial appendage resulted in a high incidence of repetitive atrial responses, which were suppressed by treatment with HT. Our results suggest that HT treatment is effective in suppressing AII-mediated atrial fibrosis and AF via induction of HSP72 at least in parts, and is thus expected to be a novel strategy for prevention of AF.
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Affiliation(s)
- Osamu Wakisaka
- Department of Internal Medicine 1, Faculty of Medicine, Oita University, Oita, 1-1 Idaigaoka, Hasama, Oita 879-5593, Japan
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5
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Skoumal R, Szokodi I, Aro J, Földes G, Göoz M, Seres L, Sármán B, Lakó-Futó Z, Papp L, Vuolteenaho O, Leppäluoto J, DeChâtel R, Ruskoaho H, Tóth M. Involvement of endogenous ouabain-like compound in the cardiac hypertrophic process in vivo. Life Sci 2007; 80:1303-10. [PMID: 17266992 DOI: 10.1016/j.lfs.2006.12.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 12/09/2006] [Accepted: 12/15/2006] [Indexed: 11/18/2022]
Abstract
The Na(+)/K(+)-ATPase inhibitor ouabain has been shown to trigger hypertrophic growth of cultured cardiomyocytes; however, the significance of endogenous ouabain-like compound (OLC) in the hypertrophic process in vivo is unknown. Here we characterized the involvement of OLC in left ventricular (LV) hypertrophy induced by norepinephrine (NE) and angiotensin II (Ang II) infusions in rats. Administration of NE (300 microg/kg/h) via subcutanously implanted osmotic minipumps for 72 h resulted in a significant increase in left ventricular weight to body weight (LVW/BW) ratio (P<0.001) and a substantial up-regulation of atrial natriuretic peptide (ANP) gene expression (13.2-fold, P<0.001). NE infusion induced a transient increase in plasma OLC levels at 12 h (P<0.05), which returned to control levels by 72 h. Adrenalectomy markedly reduced both basal and NE-induced increase in plasma OLC levels. LVW/BW ratio was not modulated by adrenalectomy; however, ANP gene expression was blunted by 44% (P<0.01) and 47% (P<0.05) at 12 and 72 h, respectively. In agreement, adrenalectomy reduced up-regulation of ANP without affecting LV mass in rats infused with Ang II (33 microg/kg/h). Administration of exogenous ouabain (1 nM to 100 microM) for 24 h had no effect on ANP gene expression in cultured neonatal rat ventricular myocytes. However, the up-regulation of ANP mRNA levels induced by the alpha-adrenergic agonist phenylephrine (1 microM) was markedly enhanced by ouabain (100 microM) (5.6-fold vs. 9.6-fold, P<0.01). These data show that OLC as an adrenal-derived factor may be required for the induction LV ANP gene expression during the hypertrophic process.
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MESH Headings
- Adrenalectomy
- Angiotensin II/pharmacology
- Animals
- Atrial Natriuretic Factor/genetics
- Blotting, Northern
- Cardenolides/blood
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Gene Expression/drug effects
- Hypertrophy, Left Ventricular/blood
- Hypertrophy, Left Ventricular/chemically induced
- Hypertrophy, Left Ventricular/genetics
- Male
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Norepinephrine/pharmacology
- Organ Size/drug effects
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Saponins/blood
- Up-Regulation/drug effects
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Réka Skoumal
- 1st Department of Medicine, Semmelweis University, Budapest H-1083, Hungary; Szentágothai János Knowledge Center, Semmelweis University, Budapest H-1085, Hungary
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Hwang GS, Oh KS, Koo HN, Seo HW, You KH, Lee BH. Effects of KR-31378, a novel ATP-sensitive potassium channel activator, on hypertrophy of H9c2 cells and on cardiac dysfunction in rats with congestive heart failure. Eur J Pharmacol 2006; 540:131-8. [PMID: 16729997 DOI: 10.1016/j.ejphar.2006.04.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2006] [Revised: 04/18/2006] [Accepted: 04/19/2006] [Indexed: 10/24/2022]
Abstract
The present study was performed to evaluate the effects of (2S, 3S, 4R)-N"-cyano-N-(6-amino-3, 4-dihydro-2-dimethoxymethyl-3-hydroxy-2-methyl-2H-1-benzopyran-4yl)-N'-benzylguanidine (KR-31378), a novel mitochondrial ATP-sensitive potassium channel activator, on hypertrophy of H9c2 cells and on cardiac dysfunction in rats with congestive heart failure. In rat heart-derived H9c2 cells treated with hypertrophic agonists, such as angiotensin II, phenylephrine, isoproterenol, and urotensin II, cell size was significantly increased by 27-47%. The increases in cell size induced by the hypertrophic agonists were inhibited by treatment of KR-31378 in a concentration-dependent manner. This was confirmed by the results showing that KR-31378 inhibited the angiotensin II-induced increase in cell protein content. The effect of KR-31378 on the angiotensin II-induced increase in cell size was reversed by mitochondrial ATP-sensitive potassium channel blockers, 5-hydroxydecanoate or glibenclamide. In rats with congestive heart failure, induced by permanent coronary artery occlusion for 8 weeks, KR-31378 significantly reversed the cardiac dysfunction (increase in ratios of stroke volume or cardiac output to body weight) induced by myocardial infarction without reducing infarct size. In addition, KR-31378 significantly inhibited atrial hypertrophy (decrease in ratio of right atrium to body weight) and decreased the serum pro-atrial natriuretic peptide level, a biochemical marker of heart failure. These results suggest that KR-31378 suppresses hypertrophy induced by hypertrophic agonists in H9c2 cells and improves cardiac dysfunction in rats with congestive heart failure induced by myocardial infarction, and that the effects may be mediated by the activation of mitochondrial ATP-sensitive potassium channels.
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Affiliation(s)
- Geum Shil Hwang
- Medicinal Science Division, Korea Research Institute of Chemical Technology, #100, Jangdong, Yuseong, Daejon, 305-343, South Korea
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Sanghi S, Kumar R, Smith M, Baker KM, Dostal DE. Activation of protein kinase A by atrial natriuretic peptide in neonatal rat cardiac fibroblasts: role in regulation of the local renin-angiotensin system. ACTA ACUST UNITED AC 2005; 132:1-8. [PMID: 16194576 DOI: 10.1016/j.regpep.2005.06.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Revised: 03/15/2005] [Accepted: 06/15/2005] [Indexed: 11/12/2022]
Abstract
There is an inverse relationship between renin and atrial natriuretic peptide (ANP) levels in the plasma. Since both the ANP and renin-angiotensin system (RAS) are upregulated in development and cardiac hypertrophy, we tested whether ANP differentially regulates RAS in cardiac cells. Cardiac fibroblasts isolated from neonatal rats were treated with ANP(1-28), a biologically active fragment of ANP. Renin and angiotensinogen (Ao) mRNA levels were measured by quantitative multiplex RT-PCR and protein levels determined by Western blot analysis. ANP(1-28) increased renin and Ao mRNA levels (737+/-131% and 178+/-51.3%) with EC50 values of 4.12+/-0.3 and 8.67+/-0.22 nmol/L, respectively. At the protein level, secretion of renin and Ao was significantly enhanced resulting in approximately 4-fold increase in ANG II level in the medium. The effect of ANP(1-28) on renin and Ao mRNA expression were reproduced by 8-bromo-cyclic GMP. Inhibition of protein kinase G (PKG) with KT5823 blunted ANP(1-28)-induced upregulation of renin, but not Ao mRNA, while inhibition of protein kinase A (PKA) with KT5720 attenuated the upregulation of both renin and Ao mRNA. These findings suggest that unlike in plasma, ANP positively regulates the RAS in cardiac fibroblasts, which may have a significant role in development of the fetal heart.
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Affiliation(s)
- Sandhya Sanghi
- Division of Molecular Cardiology, Cardiovascular Research Institute, The Texas A&M University System Health Science Center, College of Medicine, TX, USA
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Lee KS, Kim SY, Han JH, Kim YA, Cao C, Kim SZ, Cho KW, Kim SH. Different responses of atrial natriuretic peptide secretion and its receptor density to salt intake in rats. Exp Biol Med (Maywood) 2004; 229:65-71. [PMID: 14709778 DOI: 10.1177/153537020422900108] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This study investigated whether high-salt intake influences atrial natriuretic peptide (ANP) system, atrial content, and release rate of ANP as well as receptor density in the kidney were measured in salt intake rats. Male Sprague-Dawley rats received either 0.9% or 2% salt in their drinking water for 10 days. The stretch-induced ANP secretion from isolated perfused non-beating left atria was accentuated, and the production of cGMP by ANP in renal cortical tissue membranes were pronounced in rats exposed to 0.9% salt for 10 days but not in rats exposed to 2% salt. The levels of ANP receptor density and expression in renal cortex were decreased in 2% salt intake rats but not in 0.9% salt intake rats. No significant differences in atrial and plasma concentrations of ANP and water balance were observed in both salt intakes. Therefore, these results suggest that atrial ANP secretion and its binding sites in the kidney may respond differently to ingested salt concentrations in rats.
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Affiliation(s)
- Kyung Sun Lee
- Department of Physiology, Medical School, Institute for Medical Sciences, Chonbuk National University, Jeonju 561-180, Korea
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Hwang ISS, Cheung BMY, Tang F. Increase in adrenomedullin gene expression in the left atrium and ventricle in the two-kidney one-clip renovascular hypertensive rats. Neuropeptides 2003; 37:239-44. [PMID: 12906842 DOI: 10.1016/s0143-4179(03)00052-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The 2-kidney 1-clip rat model was set up by clipping the left renal artery. At 5 weeks after clipping, there was an increase in preproadrenomedullin mRNA levels in both the left atria and the left ventricle. Adrenomedullin (AM) contents, however, increased in the left ventricle but decreased in the left atrium. These changes were not observed at 2 weeks after clipping. There were no changes in AM or preproadrenomedullin mRNA levels in the thoracic aorta and the mesenteric artery, and in plasma AM levels at 2 weeks or 5 weeks after clipping. We concluded that there was an increase in the secretion of AM in the left ventricle and the left atria in the 5 week renovascular hypertensive rat. The lack of change in plasma AM level suggests a paracrine function for the peptide in this setting.
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Affiliation(s)
- Isabel S S Hwang
- Department of Physiology, Faculty of Medicine, The University of Hong Kong, Sassoon Road, Pokfulam, Hong Kong, China
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Kim SH, Cao C, Han JH, Kim SZ, Cho KW. Attenuation of negatively regulated ANP secretion by calcium in hypertrophied atria. REGULATORY PEPTIDES 2002; 105:181-8. [PMID: 11959372 DOI: 10.1016/s0167-0115(02)00014-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abnormal intracellular Ca(2+)-handling has been described in various heart diseases associated with cardiac hypertrophy. The crucial role of Ca(2+) in the excitation-secretion coupling in atrial cardiomyocytes is not well established. To investigate modulation of atrial natriuretic peptide (ANP) secretion regulated by Ca(2+) in hypertrophied atria, responsiveness of stretch-induced ANP to Ca(2+) was studied using isolated perfused quiescent hypertrophied rat atria. Male Sprague-Dawley rats were given a single subcutaneous injection of 50 mg/kg monocrotaline (MCT) and were sacrificed at 5-6 weeks. In isolated perfused hypertrophied right atria from MCT rats, changes in atrial volume induced by increased atrial pressure caused proportional increases in mechanically stimulated extracellular fluid (ECF) translocation and stretch-induced ANP secretion. Stretch-induced ANP secretion was markedly increased by the depletion of extracellular Ca(2+). However, an accentuation of stretch-induced ANP secretion by Ca(2+) depletion was markedly attenuated in hypertrophied right atria, as compared to control right atria. Therefore, stretch-induced ANP secretion in terms of ECF translocation by Ca(2+) depletion in hypertrophied atria was significantly lower than in control right atria. However, no significant differences were observed between nonhypertrophied and control left atria. Depletion of extracellular Ca(2+) caused a decrease in intracellular calcium in single beating atrial myocytes, which was significantly attenuated in hypertrophied atrial myocytes. The results suggest that attenuation of Ca(2+)-induced negative regulation of ANP secretion in hypertrophied atria may be due to the disturbance of intracellular Ca(2+) regulation.
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Affiliation(s)
- Suhn Hee Kim
- Department of Physiology, Medical School, Institute for Medical Sciences, Jeonbug National University, 2-20 Keum-Am-Dong-San, Jeonju 560-180, South Korea.
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Kim SH, Han JH, Lim SH, Lee SJ, Kim SZ, Cho KW. Attenuation of inhibitory effect of CNP on the secretion of ANP from hypertrophied atria. Am J Physiol Regul Integr Comp Physiol 2001; 281:R1456-63. [PMID: 11641116 DOI: 10.1152/ajpregu.2001.281.5.r1456] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It has been shown that atrial natriuretic peptide (ANP) influences proliferation of cardiac cells. To define the possible role of C-type natriuretic peptide (CNP) in cardiac hypertrophy, the influence of CNP on the secretion of ANP was studied with the use of perfused nonbeating atria from monocrotaline-treated rats. Increases in atrial volume caused proportional increases in ANP secretion that were markedly suppressed by CNP (10(-6) M) in nonhypertrophied left atria and control right atria but not in hypertrophied right atria. However, increases in atrial volume and mechanically stimulated extracellular fluid (ECF) translocation by CNP were similar to those in the control group. Therefore, the secretion of ANP in terms of ECF translocation was decreased by CNP in nonhypertrophied left and control right atria but not in hypertrophied atria. However, the inhibitory effect of 8-bromo-cGMP on the secretion of ANP was observed in both atria. The cGMP productions from perfused hypertrophied atria and their membranes exposed to CNP were significantly lower than those from nonhypertrophied atria. No significant difference in natriuretic peptide receptor-B transcript was found. Therefore, attenuation of the inhibitory effect of CNP on the ANP secretion in hypertrophied atria may be due to lack of cGMP production. The results showing the relief of CNP-induced negative inhibition of ANP secretion by atrial hypertrophy suggest that CNP may be a contributing factor to delay the development of cardiac hypertrophy.
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Affiliation(s)
- S H Kim
- Department of Physiology, Medical School, Institute for Medical Sciences, Jeonbug National University, Jeonju 560-180, Korea.
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Kim SH, Lee KS, Kim YA, Seul KH, Kim SZ, Cho KW. Accentuation of ANP secretion to endothelin-1 in hypertrophied atria. REGULATORY PEPTIDES 2001; 102:21-9. [PMID: 11600207 DOI: 10.1016/s0167-0115(01)00301-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To investigate modulation of ANP secretion by atrial hypertrophy, the secretion of ANP in response to stretch and endothelin-1 was studied using isolated perfused quiescent atria from rats treated with monocrotaline (MCT). Male Sprague-Dawley rats were given a single subcutaneous injection of 50 mg/kg MCT or saline and were sacrificed at 6 weeks. Rats with right heart hypertrophy showed an increase in ANP mRNA and decrease in tissue concentration of ANP in hypertrophied atria and a marked increase in plasma concentration of ANP. In isolated perfused hypertrophied right atria from MCT rats, changes in atrial volume induced by increased atrial pressure caused proportional increases in mechanically stimulated extracellular fluid (ECF) translocation and stretch-activated ANP secretion. Changes in atrial volume and mechanically stimulated ECF translocation in hypertrophied right atria were not different from those in control right atria. The stretch-activated ANP secretion was suppressed without significant difference in basal ANP secretion, as compared to control right atria. Therefore, the stretch-activated ANP secretion from hypertrophied right atria into the atrial lumen in relation to the ECF translocation (ANP concentration in the interstitium) was lower than that from control atria. A positive correlation between the stretch-activated ANP secretion in relation to the ECF translocation and tissue ANP content was found in control atria but not in hypertrophied atria. Endothelin-1 caused increases in stretch-activated ANP secretion in a dose-dependent manner, which were accentuated in hypertrophied right atria. Therefore, we suggest that atrial hypertrophy causes an attenuated response to stretch and accentuated response to endothelin-1 of ANP secretion.
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Affiliation(s)
- S H Kim
- Department of Physiology, Medical School, Institute for Medical Sciences, Jeonbug National University, 2-20 Keum-Am-Dong-San, Jeonju 560-180, South Korea.
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13
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Lee J, Lee SH, Kang DG, Kim SW. Effects of nitric oxide synthesis inhibition on the atrial natriuretic peptide system. Pharmacol Res 2000; 42:275-9. [PMID: 10945935 DOI: 10.1006/phrs.2000.0687] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was aimed at investigating whether nitric oxide (NO) has a modulatory effect on the atrial natriuretic peptide (ANP) system. The atrial tissue expression of ANP mRNA was determined in rats treated with an inhibitor of NO synthesis, N(G)-nitro-L-arginine methyl ester (L-NAME), for 4 weeks. Measurements of ANP peptides and NO metabolites in the plasma and atria were also taken. The blood pressure was increased by the treatment with L-NAME (40 mg l(-1)drinking water). The atrial expression of ANP mRNA was increased. Atrial natriuretic peptides were also increased, while NO metabolites decreased in the plasma and atrial tissue. An antihypertensive treatment with losartan reversed the blood pressure to the control level. However, the atrial expression of ANP mRNA was not affected but remained at an increased level. Accordingly, the plasma ANP was elevated and NO decreased. Supplementation with L-arginine, the substrate to NO synthase, prevented the changes induced by L-NAME. These results suggest that the synthesis and release of ANP be regulated by local release of NO with a transcriptional inhibition.
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Affiliation(s)
- J Lee
- Department of Physiology, Chonnam University Medical School, Kwangju 501-190, Korea.
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Yalçin F, Aksoy FG, Muderrisoglu H, Sabah I, Garcia MJ, Thomas JD. Treatment of hypertension with perindopril reduces plasma atrial natriuretic peptide levels, left ventricular mass, and improves echocardiographic parameters of diastolic function. Clin Cardiol 2000; 23:437-41. [PMID: 10875035 PMCID: PMC6655007 DOI: 10.1002/clc.4960230612] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/1999] [Accepted: 08/26/1999] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Hypertension is a major independent risk factor for cardiac deaths, and diastolic dysfunction is a usual finding during the course of this disease. HYPOTHESIS This study was designed to investigate the effects of chronic therapy with perindopril on left ventricular (LV) mass, left atrial size, diastolic function, and plasma level of atrial natriuretic peptide (ANP) in patients with hypertension. METHODS Twenty four patients who had not been previously taking any antihypertensive medication and without prior history of angina pectoris, myocardial infarction, congestive heart failure, dysrhythmias, valvular heart disease, or systemic illnesses received 4-8 mg/day of perindopril orally. Echocardiographic studies were acquired at baseline and 6 months after the initiation of therapy. RESULTS Systolic and diastolic blood pressure decreased from 174 +/- 19.7 and 107.5 +/- 7.8 mmHg to 134 +/- 10.6 and 82 +/- 6.7 mmHg, respectively (p < 0.001). Left ventricular mass decreased from 252.4 +/- 8.3 to 205.7 +/- 7.08 g and left atrial volume from 20.4 +/- 5.1 to 17.6 +/- 5.2 ml, respectively (p < 0.001). Transmitral Doppler early and atrial filling velocity ratio (E/A) increased from 0.69 +/- 0.06 to 0.92 +/- 0.05 m/s and plasma ANP level decreased from 71.9 +/- 11.7 to 35.3 +/- 7.8 pg/ml (p < 0.001). Reduction of LV mass correlated positively with a reduction in ANP levels (r = 0.66, p < 0.0005). CONCLUSIONS Perindopril caused a significant reduction of LV mass, left atrial volume, and plasma ANP levels, as well as improvement in Doppler parameters of LV filling in this group of patients with hypertension.
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Affiliation(s)
- F Yalçin
- Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA
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15
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Partovian C, Adnot S, Eddahibi S, Teiger E, Levame M, Dreyfus P, Raffestin B, Frelin C. Heart and lung VEGF mRNA expression in rats with monocrotaline- or hypoxia-induced pulmonary hypertension. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H1948-56. [PMID: 9843792 DOI: 10.1152/ajpheart.1998.275.6.h1948] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that is upregulated during exposure to hypoxia. In this study, we analyzed heart and lung VEGF mRNA expression and examined pulmonary vascular remodeling as well as myocardial capillary density in two rat models of pulmonary hypertension involving exposure to chronic hypoxia (CH) and treatment with monocrotaline (MCT), respectively. The rats were studied after 0.5, 1, 3, 15, and 30 days of exposure to 10% O2 or 1, 6, and 30 days after a subcutaneous MCT injection (60 mg/kg). Both CH and MCT induced pulmonary hypertension and hypertrophy of the right ventricle (RV) with increased RV weight and atrial natriuretic peptide mRNA expression. VEGF mRNA expression as assessed by Northern blot analysis was potently induced after 12 h of hypoxia in both the right and left ventricles. After prolonged exposure to hypoxia, VEGF mRNA returned to baseline in the left ventricle (LV) but remained increased in the RV, where it peaked after 30 days. In MCT rats, VEGF mRNA was unchanged in the LV but decreased by 50% in the RV and by 90% in the lungs after 30 days. VEGF mRNA remained unchanged in the lungs from CH rats. Pulmonary vascular remodeling was more pronounced in MCT than in CH rats. The number of capillaries per RV myocyte was increased in rats exposed to 30 days of hypoxia, whereas it remained unchanged in MCT rats despite a similar degree of RV hypertrophy. Our results suggest that the sustained increase in VEGF expression in the hypertrophied RV during CH may account for the increased number of capillaries per myocyte. In contrast, reduced VEGF expression in the lungs and RV of MCT rats may aggravate pulmonary vascular remodeling and compromise RV myocardial perfusion.
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Affiliation(s)
- C Partovian
- Service de Pharmacologie Clinique, Département de Physiologie, Institut National de la Santé et de la Recherche Médicale Unité 492 and 421, Hôpital Henri Mondor, 94010 Créteil, France
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16
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Fahy GJ, McCreery CJ, O'Sullivan F, Keenan AK, Quigley PJ, Maurer BJ. Plasma atrial natriuretic peptide is elevated in patients with hypertrophic cardiomyopathy. Int J Cardiol 1996; 55:149-55. [PMID: 8842784 DOI: 10.1016/0167-5273(96)02662-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
STUDY OBJECTIVES To determine if plasma levels of atrial natriuretic peptide are elevated in patients with hypertrophic cardiomyopathy and to determine the relationship of atrial natriuretic peptide to symptoms and echocardiographic indices of left ventricular structure and diastolic function in these patients. DESIGN A prospective study in which atrial natriuretic peptide was measured in peripheral venous plasma in 14 patients (age 44 +/- 14 years) with hypertrophic cardiomyopathy and 17 healthy controls. Echocardiography was performed in all cases and 30 controls to examine indices of left heart structure and function. All patients underwent clinical evaluation. RESULTS The concentration of atrial natriuretic peptide was significantly higher in patients with hypertrophic cardiomyopathy than controls, (17.86 +/- 8.72 vs. 6.22 +/- 3.26 pmol/l, P = 0.0001). Diastolic dysfunction was observed in 11 of 14 patients with hypertrophic cardiomyopathy. No correlation was demonstrated between atrial natriuretic peptide levels and the degree of diastolic dysfunction, septal or free wall thickness, left atrial size, degree of mitral regurgitation or New York Heart Association functional class. CONCLUSIONS Plasma levels of atrial natriuretic peptide are elevated in patients with hypertrophic cardiomyopathy but do not correlate with symptoms or echocardiographically-derived indices of left ventricular structure or diastolic function.
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Affiliation(s)
- G J Fahy
- Department of Cardiology, University College, Dublin, Ireland
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17
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Matsubara H, Nio Y, Murasawa S, Kijima K, Maruyama K, Mori Y, Inada M. Regulation of gene transcription of angiotensin II receptor subtypes in the heart. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 396:23-32. [PMID: 8726682 DOI: 10.1007/978-1-4899-1376-0_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- H Matsubara
- Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan
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18
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Tsukaguchi H, Matsubara H, Taketani S, Mori Y, Seido T, Inada M. Binding-, intracellular transport-, and biosynthesis-defective mutants of vasopressin type 2 receptor in patients with X-linked nephrogenic diabetes insipidus. J Clin Invest 1995; 96:2043-50. [PMID: 7560098 PMCID: PMC185843 DOI: 10.1172/jci118252] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Nephrogenic diabetes insipidus (NDI) is most often an X-linked disorder in which urine is not concentrated due to renal resistance to arginine vasopressin. We recently identified four vasopressin type 2 receptor gene mutations in unrelated X-linked NDI families, including R143P, delta V278, R202C, and 804insG. All these mutations reduced ligand binding activity to < 10% of the normal without affecting mRNA accumulation. To elucidate whether the receptors are expressed on the cell surface, we analyzed biosynthesis and localization of tagged or untagged receptors stably expressed in Chinese hamster ovary (CHO) cells, using two antibodies directed against distinct termini. Whole-cell and surface labeling studies revealed that the R202C clone had both surface-localized (50-55 kD) and intracellular proteins (40 and 75 kD), similar to the wild-type AVPR2 clone, whereas the R143P and delta V278 clones lacked the surface receptors, despite relatively increased intracellular components. The 804insG mutant cell produced no proteins despite an adequate mRNA level. Immunofluorescence staining confirmed that the R202C mutant reaches the cell surface, whereas the R143P and delta V278 mutants are retained within the cytoplasmic compartment. Thus, R202C, R143P/delta V278, and 804insG result in three distinct phenotypes, that is, a simple binding impairment at the cell surface, blocked intracellular transport, and ineffective biosynthesis or/and accelerated degradation of the receptor, respectively, and therefore are responsible for NDI. This phenotypic classification will help understanding of molecular pathophysiology of this disorder.
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Affiliation(s)
- H Tsukaguchi
- Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan
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19
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Tsukaguchi H, Matsubara H, Inada M. Expression studies of two vasopressin V2 receptor gene mutations, R202C and 804insG, in nephrogenic diabetes insipidus. Kidney Int 1995; 48:554-62. [PMID: 7564126 DOI: 10.1038/ki.1995.327] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Nephrogenic diabetes insipidus (NDI) is a rare X-linked disorder associated with renal tubule resistance to arginine vasopressin (AVP). To understand the mechanisms of AVP resistance underlying this disorder, we have analyzed the vasopressin V2 receptor gene in two unrelated Japanese kindreds with NDI and expressed the mutants to characterize their functional properties. Direct sequencing revealed two V2 receptor gene mutations: a missense mutation from Arg202 to Cys in the third extracellular domain (R202C) and a single base insertion (G) in two consecutive GGG triplets (nucleotide 804 to 809) in the third cytoplasmic domain, resulting in a frame shift with premature termination at codon 258 (804insG). Transient expression study with COS-7 cells showed that R202C mutation reduced both binding affinity (15%) and capacity (30%), while 804insG mutation abolished binding ability. For further evaluation of the binding ability of the R202C mutant, we expressed the mutants in Chinese hamster ovary (CHO) cells. Although the mutant cell lines produced V2 receptor mRNA comparable levels to the wild-type receptor cell lines, R202C mutant cell lines had no binding ability. Our results suggest an introduction of a new cysteine residue in the extracellular domain and a receptor truncation removing one third of the carboxyl terminus could impair ligand binding activity of the V2 receptor through a post-transcriptional mechanism, thereby causing AVP resistance in the NDI patients.
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Affiliation(s)
- H Tsukaguchi
- Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan
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20
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Nio Y, Matsubara H, Murasawa S, Kanasaki M, Inada M. Regulation of gene transcription of angiotensin II receptor subtypes in myocardial infarction. J Clin Invest 1995; 95:46-54. [PMID: 7814645 PMCID: PMC295367 DOI: 10.1172/jci117675] [Citation(s) in RCA: 314] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Increasing evidence suggests that angiotensin II (AngII) acts as a modulator for ventricular remodeling after myocardial infarction. Using competitive reverse-transcriptase polymerase chain reaction, nuclear runoff, and binding assays, we examined the regulation of AngII type 1a and 1b (AT1a-R and AT1b-R) and type 2 receptor (AT2-R) expression in the infarcted rat heart as well as the effects of AngII receptor antagonists. AT1a-R mRNA levels were increased in the infarcted (4.2-fold) and noninfarcted portions (2.2-fold) of the myocardium 7 d after myocardial infarction as compared with those in sham-operated controls, whereas AT1b-R mRNA levels were unchanged. The amount of detectable AT2-R mRNA increased in infarcted (3.1-fold) and noninfarcted (1.9-fold) portions relative to that in the control. The transcription rates for AT1a-R and AT2-R genes, determined by means of a nuclear runoff assay, were significantly increased in the infarcted heart. The AngII receptor numbers were elevated (from 12 to 35 fmol/mg protein) in the infarcted myocardium in which the increases in AT1-R and AT2-R were 3.2- and 2.3-fold, respectively, while the receptor affinity was unchanged. Therapy with AT1-R antagonist for 7 d reduced the increase in AT1-R and AT2-R expressions in the infarcted heart together with a decrease in blood pressure, whereas therapy with an AT2-R antagonist did not affect mRNA levels and blood pressure. Neither AT1-R nor AT2-R antagonists affected the infarct sizes. These results demonstrated that myocardial infarction causes an increase in the gene transcription and protein expression of cardiac AT1a-R and AT2-R, whereas the AT1b-R gene is unaffected, and that therapy with an AT1-R antagonist, but not with an AT2-R antagonist, is effective in reducing the increased expression of AngII receptor subtypes induced by myocardial infarction.
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Affiliation(s)
- Y Nio
- Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan
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21
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Abstract
Extrahepatic synthesis and localization of angiotensinogen have been described in animals, thus establishing the tissue renin-angiotensin system. We examined angiotensinogen messenger RNA synthesis by northern blotting. It was detected not only in the liver, but also in both the atrial and ventricular heart tissues, suggesting that angiotensinogen is synthesized in the human heart. Immunohistochemical studies using a specific antibody to angiotensinogen revealed a stronger reaction in the endocardial layer of the human left ventricle, than in the epicardial layer, and intense immunoreactivity in the conduction system and right atrium. Furthermore, our experiments revealed a widespread immunopositive reaction for angiotensinogen in the left ventricle of diseased hearts. We examined the participation of the collagen in the occurrence and progression of cardiomyopathy. The acetic acid solubility of collagen and reducible crosslink decreased in cardiomyopathic hamsters as the fibrosis progressed, but was unchanged in controls. These findings indicate that in the early phase of cardiomyopathy the extracellular matrix of the myocardium is similar to immature tissues. In the later phase, the matrix resembles that of hard tissues, and is insoluble. Furthermore, we examined the relationship between angiotensin II and collagen synthesis. Basal collagen synthesis in cardiac fibroblasts from spontaneously hypertensive rats was 1.6-fold greater than that in Wistar-Kyoto rats. The responsiveness of collagen production to Ang II was significantly enhanced in SHR. This effect was angiotensin receptor-specific, because it was blocked by the competitive inhibitor. These results indicate angiotensin II may play an important role in collagen accumulation in hypertensive cardiac hypertrophy.
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Affiliation(s)
- H Kawaguchi
- Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Sapporo, Japan
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22
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Kanasaki M, Matsubara H, Murasawa S, Masaki H, Nio Y, Inada M. cAMP responsive element-mediated regulation of the gene transcription of the alpha 1B adrenergic receptor by thyrotropin. J Clin Invest 1994; 94:2245-54. [PMID: 7989580 PMCID: PMC330051 DOI: 10.1172/jci117587] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
To elucidate the molecular mechanism of the stimulatory effect of thyrotropin on the gene regulation of alpha 1B adrenergic receptor in functioning rat thyroid (FRTL-5) cells, we established a competitive reverse-transcriptase (RT) polymerase chain reaction (PCR) and nuclear run-off assay to quantify changes in mRNA levels and transcription rates. A binding assay showed that FRTL-5 cells predominantly expressed alpha 1B adrenergic receptor and that thyrotropin increased its expression sevenfold. By means of RT-PCR, we found that thyrotropin induced an 11-fold increase in alpha 1B receptor mRNA abundance. The nuclear run-off assay demonstrated that thyrotropin caused a ninefold increase at the gene transcriptional level, which occurred in the presence of the protein synthesis inhibitor cycloheximide. The half-life of the alpha 1B receptor mRNA in cells incubated with thyrotropin for 1 h increased 1.5-fold but returned to the original value after 12 h. Dibutyryl cAMP and forskolin mimicked the stimulatory effects of thyrotropin on the gene transcriptional level. The 5'-flanking region of the rat alpha 1B receptor gene contained a putative cAMP responsive element (CRE) at nucleotide -438 relative to the translation start site. The promoter analysis using the reporter gene indicated that the CRE motif confers the cAMP sensitivity to the transcription of the rat alpha 1B receptor gene. These results demonstrated that a CRE-mediated mechanism is involved in the transcriptional regulation of the alpha 1B receptor gene by thyrotropin without requiring new protein synthesis.
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Affiliation(s)
- M Kanasaki
- Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan
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23
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Affiliation(s)
- A Monopoli
- Research Laboratories, Schering-Plough S.p.A., Milan, Italy
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24
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Murasawa S, Matsubara H, Urakami M, Inada M. Regulatory elements that mediate expression of the gene for the angiotensin II type 1a receptor for the rat. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74209-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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25
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Matsubara H, Suzuki J, Inada M. Shaker-related potassium channel, Kv1.4, mRNA regulation in cultured rat heart myocytes and differential expression of Kv1.4 and Kv1.5 genes in myocardial development and hypertrophy. J Clin Invest 1993; 92:1659-66. [PMID: 7691883 PMCID: PMC288324 DOI: 10.1172/jci116751] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The multiple K+ channels are crucial for repolarization and configuration of the action potential in the neuronal and cardiac cells. In this study, we report the regulatory mechanisms of rapidly inactivating Shaker Kv1.4 channel transcript in the rat heart. Quantitative PCR analysis showed that stimulation with high concentration of KCl, BAY-K 8644, or 12-O-tetradecanoyl phorbol-13-acetate resulted in an immediate and substantial increase (two- to threefold) of Kv1.4 mRNA levels in spontaneously beating myocytes prepared from neonatal rat ventricles. The Kv1.4 mRNA in the ventricle remains at a steady state level after birth and gradually declines with maturation. These results suggest that the Kv1.4 mRNA level is not static and undergoes dynamic modulation by multiple factors that activate intracellular signals. In addition, the expression patterns of Kv1.4 as well as the delayed rectifier Shaker K+ channel Kv1.5 mRNAs were examined in hypertrophied ventricles in which a plateau phase of action potential is remarkably prolonged. The Kv1.5 mRNA level was dramatically repressed while the Kv1.4 mRNA level was remarkably increased. This differential regulation was completely reversed by the normalization of hypertrophy, suggesting that the pathological alterations of K+ channel gene regulation may be involved in the occurrence of ventricular arrhythmias in hypertrophic hearts.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Aging/physiology
- Animals
- Animals, Newborn
- Atrial Natriuretic Factor/biosynthesis
- Base Sequence
- Bucladesine/pharmacology
- Cardiomegaly/metabolism
- Cells, Cultured
- DNA Primers
- Gene Expression Regulation
- Heart/drug effects
- Heart/growth & development
- Heart Ventricles
- Molecular Sequence Data
- Myocardium/metabolism
- Nifedipine/pharmacology
- Oligonucleotides, Antisense
- Polymerase Chain Reaction/methods
- Potassium Channels/biosynthesis
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
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Affiliation(s)
- H Matsubara
- Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan
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26
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Di Nardo P, Minieri M, Carbone A, Maggiano N, Micheletti R, Peruzzi G, Tallarida G. Myocardial expression of atrial natriuretic factor gene in early stages of hamster cardiomyopathy. Mol Cell Biochem 1993; 125:179-92. [PMID: 8283973 DOI: 10.1007/bf00936447] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Ventricular cardiomyocytes represent the most important source of atrial natriuretic factor (ANF) in pathological conditions such as congestive heart failure (CHF). It has been suggested that in cardiomyopathic Syrian hamster ventricles the ANF gene can be reactivated during the hypertrophic stage occurring before heart failure. The present study was undertaken to investigate ANF gene expression during early stages of myocardial damage and its distribution throughout atrial and ventricular myocardium in UM-X7.1 cardiomyopathic Syrian hamsters (CMPH) before hypertrophy and cardiac failure occur. Atria, right and left ventricles, and interventricular septum of hearts of 20-23 days old (young) and 90-95 days old (adult) CMPH were studied. The absence of hypertrophy and cardiac failure was preliminarly ascertained by microscopic and hemodynamic evaluation. ANF-mRNA as well as tissue and plasma immunoreactive ANF were assayed. Moreover, ANF secretion pattern was evaluated by immunocytochemical techniques. Young and adult CMPH hearts were in the necrotic stage of myocardial disease, as demonstrated by histopathological evaluation and by decreased wet weights (mg/g body weight) of different heart regions. Hemodynamic assessment showed no significant changes of left ventricular end-diastolic pressure (LVEDP) and a decrease of the left ventricular peak systolic pressure (LVSP) and +dP/dt. Plasma immunoreactive ANF (IR-ANF) levels were higher in young (3-fold) and adult (6-fold) CMPH than in age-matched normal hamsters. A reduced IR-ANF concentration (per milligram protein) was observed in both young and adult cardiomyopathic atria in respect to healthy controls, whereas a higher IR-ANF concentration was present in ventricles. A 3-fold, 6-fold and 20-fold increase of IR-ANF concentration was found in right ventricular free-wall (RV), left ventricular free-wall (LV) and interventricular septum (IVS), respectively. Northern-blot analysis confirmed that IVS was the major site of ventricular ANF-mRNA transcription in both young and adult CMPH. ANF-mRNA was increased also in atria where a faster peptide secretion can be hypothesized to lower tissue IR-ANF concentration. ANF secretion in ventricular myocardium was achieved via constitutive pathway as demonstrated by immunocytochemistry. Different patterns of ANF gene reactivation occur in CMPH myocardium before intraventricular pressure increases and structural hypertrophic modifications are detectable. The extent of ANF gene reactivation in CMPH ventricles parallels the severity of necrotic damage. Moreover, ANF gene expression is heterogeneously distributed throughout the myocardium, suggesting that interventricular septum, the ontogenically youngest heart region, might preserve foetal characters which can be rapidly reactivated in pathological conditions.
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Affiliation(s)
- P Di Nardo
- Department of Internal Medicine, University of Rome Tor Vergata, Italy
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27
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Black FM, Packer SE, Parker TG, Michael LH, Roberts R, Schwartz RJ, Schneider MD. The vascular smooth muscle alpha-actin gene is reactivated during cardiac hypertrophy provoked by load. J Clin Invest 1991; 88:1581-8. [PMID: 1834699 PMCID: PMC295677 DOI: 10.1172/jci115470] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cardiac hypertrophy triggered by mechanical load possesses features in common with growth factor signal transduction. A hemodynamic load provokes rapid expression of the growth factor-inducible nuclear oncogene, c-fos, and certain peptide growth factors specifically stimulate the "fetal" cardiac genes associated with hypertrophy, even in the absence of load. These include the gene encoding vascular smooth muscle alpha-actin, the earliest alpha-actin expressed during cardiac myogenesis; however, it is not known whether reactivation of the smooth muscle alpha-actin gene occurs in ventricular hypertrophy. We therefore investigated myocardial expression of the smooth muscle alpha-actin gene after hemodynamic overload. Smooth muscle alpha-actin mRNA was discernible 24 h after coarctation and was persistently expressed for up to 30 d. In hypertrophied hearts, the prevalence of smooth muscle alpha-actin gene induction was 0.909, versus 0.545 for skeletal muscle alpha-actin (P less than 0.05). Ventricular mass after 2 d or more of aortic constriction was more highly correlated with smooth muscle alpha-actin gene activation (r = 0.852; P = 0.0001) than with skeletal muscle alpha-actin (r = 0.532; P = 0.009); P less than 0.0005 for the difference in the correlation coefficients. Thus, smooth muscle alpha-actin is a molecular marker of the presence and extent of pressure-overload hypertrophy, whose correlation with cardiac growth at least equals that of skeletal alpha-actin. Induction of smooth muscle alpha-actin was delayed and sustained after aortic constriction, whereas the nuclear oncogenes c-jun and junB were expressed rapidly and transiently, providing potential dimerization partners for transcriptional control by c-fos.
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Affiliation(s)
- F M Black
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
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28
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Abstract
The role of polypeptide growth factors in cardiovascular ontogeny, function, and pathologic states is poorly understood. Recent investigations demonstrate that the myocardium produces both known and novel growth factors, which are highly regulated during development and disease, and have suggested that peptide growth factors may direct cardiac organogenesis and adaptation. Aspects of growth factor production, transduction, and action in myocardium are distinct to the cardiac muscle lineage and were not foreseen from results in simpler systems. Transforming growth factor beta 1 and fibroblast growth factors (FGFs) selectively up-regulate an ensemble of tissue-specific genes associated with the fetal myocardium. One of these, encoding the skeletal muscle isoform of alpha-actin, is activated by basic FGF yet is inhibited by acidic FGF. A serum response element of this gene is selectively induced, in cardiac myocytes, by basic FGF but not acidic FGF. Thus, cardiac muscle is an especially intriguing model for the analysis of growth factor signalling pathways that control differentiated gene transcription.
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Affiliation(s)
- M D Schneider
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030
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