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van der Laarse WJ, Bogaards SJP, Schalij I, Vonk Noordegraaf A, Vaz FM, van Groen D. Work and oxygen consumption of isolated right ventricular papillary muscle in experimental pulmonary hypertension. J Physiol 2022; 600:4465-4484. [PMID: 35993114 DOI: 10.1113/jp282991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 08/12/2022] [Indexed: 11/08/2022] Open
Abstract
Right-sided myocardial mechanical efficiency (work output/metabolic energy input) in pulmonary hypertension can be severely reduced. We determined the contribution of intrinsic myocardial determinants of efficiency using papillary muscle preparations from monocrotaline-induced pulmonary hypertensive (MCT-PH) rats. The hypothesis tested was that efficiency is reduced by mitochondrial dysfunction in addition to increased activation heat reported previously. Right ventricular muscle preparations were subjected to 5 Hz sinusoidal length changes at 37°C. Work and suprabasal oxygen consumption (V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ ) were measured before and after cross-bridge inhibition by blebbistatin. Cytosolic cytochrome c concentration, myocyte cross-sectional area, proton permeability of the inner mitochondrial membrane and monoamine oxidase and glucose 6-phosphate dehydrogenase activities and phosphatidylglycerol/cardiolipin contents were determined. Mechanical efficiency ranged from 23% to 11% in control (n = 6) and from 22% to 1% in MCT-PH (n = 15) and correlated with work (r2 = 0.68, P < 0.0001) but not withV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ (r2 = 0.004, P = 0.7919).V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ for cross-bridge cycling was proportional to work (r2 = 0.56, P = 0.0005). Blebbistatin-resistantV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ (r2 = 0.32, P = 0.0167) and proton permeability of the mitochondrial inner membrane (r2 = 0.36, P = 0.0110) correlated inversely with efficiency. Together, these variables explained the variance of efficiency (coefficient of multiple determination r2 = 0.79, P = 0.0001). Cytosolic cytochrome c correlated inversely with work (r2 = 0.28, P = 0.0391), but not with efficiency (r2 = 0.20, P = 0.0867). Glucose 6-phosphate dehydrogenase, monoamine oxidase and phosphatidylglycerol/cardiolipin increased in the right ventricular wall of MCT-PH but did not correlate with efficiency. Reduced myocardial efficiency in MCT-PH is a result of activation processes and mitochondrial dysfunction. The variance of work and the ratio of activation heat reported previously and blebbistatin-resistantV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ are discussed. KEY POINTS: Mechanical efficiency of right ventricular myocardium is reduced in pulmonary hypertension. Increased energy use for activation processes has been demonstrated previously, but the contribution of mitochondrial dysfunction is unknown. Work and oxygen consumption are determined during work loops. Oxygen consumption for activation and cross-bridge cycling confirm the previous heat measurements. Cytosolic cytochrome c concentration, proton permeability of the mitochondrial inner membrane and phosphatidylglycerol/cardiolipin are increased in experimental pulmonary hypertension. Reduced work and mechanical efficiency are related to mitochondrial dysfunction. Upregulation of the pentose phosphate pathway and a potential gap in the energy balance suggest mitochondrial dysfunction in right ventricular overload is a resiult of the excessive production of reactive oxygen species.
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Affiliation(s)
- Willem J van der Laarse
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Sylvia J P Bogaards
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Ingrid Schalij
- Department of Pulmonology, Amsterdam Cardiovascular Sciences, VU University Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Anton Vonk Noordegraaf
- Department of Pulmonology, Amsterdam Cardiovascular Sciences, VU University Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Frédéric M Vaz
- Amsterdam Cardiovascular Sciences, VU University Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands and Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
- Department of Clinical Chemistry, Amsterdam Gastroentrology Endocrinology Metabolism, Amsterdam, Department of Pediatrics, Amsterdam University Medical Centers, Amsterdam, The Netherlands
- Emma Children's Hospital, Amsterdam University Medical Centers, Core Facility Metabolomics, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Duncan van Groen
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
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Palanisamy AP, Suryakumar G, Panneerselvam K, Willey CD, Kuppuswamy D. A Kinase-Independent Function of c-Src Mediates p130Cas Phosphorylation at the Serine-639 Site in Pressure Overloaded Myocardium. J Cell Biochem 2016; 116:2793-803. [PMID: 25976166 DOI: 10.1002/jcb.25224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/08/2015] [Indexed: 12/11/2022]
Abstract
Early work in pressure overloaded (PO) myocardium shows that integrins mediate focal adhesion complex formation by recruiting the adaptor protein p130Cas (Cas) and nonreceptor tyrosine kinase c-Src. To explore c-Src role in Cas-associated changes during PO, we used a feline right ventricular in vivo PO model and a three-dimensional (3D) collagen-embedded adult cardiomyocyte in vitro model that utilizes a Gly-Arg-Gly-Asp-Ser (RGD) peptide for integrin stimulation. Cas showed slow electrophoretic mobility (band-shifting), recruitment to the cytoskeleton, and tyrosine phosphorylation at 165, 249, and 410 sites in both 48 h PO myocardium and 1 h RGD-stimulated cardiomyocytes. Adenoviral mediated expression of kinase inactive (negative) c-Src mutant with intact scaffold domains (KN-Src) in cardiomyocytes did not block the RGD stimulated changes in Cas. Furthermore, expression of KN-Src or kinase active c-Src mutant with intact scaffold function (A-Src) in two-dimensionally (2D) cultured cardiomyocytes was sufficient to cause Cas band-shifting, although tyrosine phosphorylation required A-Src. These data indicate that c-Src's adaptor function, but not its kinase function, is required for a serine/threonine specific phosphorylation(s) responsible for Cas band-shifting. To explore this possibility, Chinese hamster ovary cells that stably express Cas were infected with either β-gal or KN-Src adenoviruses and used for Cas immunoprecipitation combined with mass spectrometry analysis. In the KN-Src expressing cells, Cas showed phosphorylation at the serine-639 (human numbering) site. A polyclonal antibody raised against phospho-serine-639 detected Cas phosphorylation in 24-48 h PO myocardium. Our studies indicate that c-Src's adaptor function mediates serine-639 phosphorylation of Cas during integrin activation in PO myocardium.
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Affiliation(s)
- Arun P Palanisamy
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425-2221
| | - Geetha Suryakumar
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425-2221
| | - Kavin Panneerselvam
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425-2221
| | - Christopher D Willey
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425-2221
| | - Dhandapani Kuppuswamy
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425-2221
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Vascular Remodeling–Associated Hypertension Leads to Left Ventricular Hypertrophy and Contractile Dysfunction in Profilin-1 Transgenic Mice. J Cardiovasc Pharmacol 2012; 60:544-52. [DOI: 10.1097/fjc.0b013e318271225d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Cheng G, Kasiganesan H, Baicu CF, Wallenborn JG, Kuppuswamy D, Cooper G. Cytoskeletal role in protection of the failing heart by β-adrenergic blockade. Am J Physiol Heart Circ Physiol 2011; 302:H675-87. [PMID: 22081703 DOI: 10.1152/ajpheart.00867.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Formation of a dense microtubule network that impedes cardiac contraction and intracellular transport occurs in severe pressure overload hypertrophy. This process is highly dynamic, since microtubule depolymerization causes striking improvement in contractile function. A molecular etiology for this cytoskeletal alteration has been defined in terms of type 1 and type 2A phosphatase-dependent site-specific dephosphorylation of the predominant myocardial microtubule-associated protein (MAP)4, which then decorates and stabilizes microtubules. This persistent phosphatase activation is dependent upon ongoing upstream activity of p21-activated kinase-1, or Pak1. Because cardiac β-adrenergic activity is markedly and continuously increased in decompensated hypertrophy, and because β-adrenergic activation of cardiac Pak1 and phosphatases has been demonstrated, we asked here whether the highly maladaptive cardiac microtubule phenotype seen in pathological hypertrophy is based on β-adrenergic overdrive and thus could be reversed by β-adrenergic blockade. The data in this study, which were designed to answer this question, show that such is the case; that is, β(1)- (but not β(2)-) adrenergic input activates this pathway, which consists of Pak1 activation, increased phosphatase activity, MAP4 dephosphorylation, and thus the stabilization of a dense microtubule network. These data were gathered in a feline model of severe right ventricular (RV) pressure overload hypertrophy in response to tight pulmonary artery banding (PAB) in which a stable, twofold increase in RV mass is reached by 2 wk after pressure overloading. After 2 wk of hypertrophy induction, these PAB cats during the following 2 wk either had no further treatment or had β-adrenergic blockade. The pathological microtubule phenotype and the severe RV cellular contractile dysfunction otherwise seen in this model of RV hypertrophy (PAB No Treatment) was reversed in the treated (PAB β-Blockade) cats. Thus these data provide both a specific etiology and a specific remedy for the abnormal microtubule network found in some forms of pathological cardiac hypertrophy.
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Affiliation(s)
- Guangmao Cheng
- Gazes Cardiac Research Institute, PO Box 250773, Medical Univ. of South Carolina, 114 Doughty St., Charleston, SC 29403, USA
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5
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Harston RK, McKillop JC, Moschella PC, Van Laer A, Quinones LS, Baicu CF, Balasubramanian S, Zile MR, Kuppuswamy D. Rapamycin treatment augments both protein ubiquitination and Akt activation in pressure-overloaded rat myocardium. Am J Physiol Heart Circ Physiol 2011; 300:H1696-706. [PMID: 21357504 DOI: 10.1152/ajpheart.00545.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ubiquitin-mediated protein degradation is necessary for both increased ventricular mass and survival signaling for compensated hypertrophy in pressure-overloaded (PO) myocardium. Another molecular keystone involved in the hypertrophic growth process is the mammalian target of rapamycin (mTOR), which forms two distinct functional complexes: mTORC1 that activates p70S6 kinase-1 to enhance protein synthesis and mTORC2 that activates Akt to promote cell survival. Independent studies in animal models show that rapamycin treatment that alters mTOR complexes also reduces hypertrophic growth and increases lifespan by an unknown mechanism. We tested whether the ubiquitin-mediated regulation of growth and survival in hypertrophic myocardium is linked to the mTOR pathway. For in vivo studies, right ventricle PO in rats was conducted by pulmonary artery banding; the normally loaded left ventricle served as an internal control. Rapamycin (0.75 mg/kg per day) or vehicle alone was administered intraperitoneally for 3 days or 2 wk. Immunoblot and immunofluorescence imaging showed that the level of ubiquitylated proteins in cardiomyocytes that increased following 48 h of PO was enhanced by rapamycin. Rapamycin pretreatment also significantly increased PO-induced Akt phosphorylation at S473, a finding confirmed in cardiomyocytes in vitro to be downstream of mTORC2. Analysis of prosurvival signaling in vivo showed that rapamycin increased PO-induced degradation of phosphorylated inhibitor of κB, enhanced expression of cellular inhibitor of apoptosis protein 1, and decreased active caspase-3. Long-term rapamycin treatment in 2-wk PO myocardium blunted hypertrophy, improved contractile function, and reduced caspase-3 and calpain activation. These data indicate potential cardioprotective benefits of rapamycin in PO hypertrophy.
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Affiliation(s)
- Rebecca K Harston
- Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, South Caroline, USA
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Cheng G, Takahashi M, Shunmugavel A, Wallenborn JG, DePaoli-Roach AA, Gergs U, Neumann J, Kuppuswamy D, Menick DR, Cooper G. Basis for MAP4 dephosphorylation-related microtubule network densification in pressure overload cardiac hypertrophy. J Biol Chem 2010; 285:38125-40. [PMID: 20889984 DOI: 10.1074/jbc.m110.148650] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Increased activity of Ser/Thr protein phosphatases types 1 (PP1) and 2A (PP2A) during maladaptive cardiac hypertrophy contributes to cardiac dysfunction and eventual failure, partly through effects on calcium metabolism. A second maladaptive feature of pressure overload cardiac hypertrophy that instead leads to heart failure by interfering with cardiac contraction and intracellular transport is a dense microtubule network stabilized by decoration with microtubule-associated protein 4 (MAP4). In an earlier study we showed that the major determinant of MAP4-microtubule affinity, and thus microtubule network density and stability, is site-specific MAP4 dephosphorylation at Ser-924 and to a lesser extent at Ser-1056; this was found to be prominent in hypertrophied myocardium. Therefore, in seeking the etiology of this MAP4 dephosphorylation, we looked here at PP2A and PP1, as well as the upstream p21-activated kinase 1, in maladaptive pressure overload cardiac hypertrophy. The activity of each was increased persistently during maladaptive hypertrophy, and overexpression of PP2A or PP1 in normal hearts reproduced both the microtubule network phenotype and the dephosphorylation of MAP4 Ser-924 and Ser-1056 seen in hypertrophy. Given the major microtubule-based abnormalities of contractile and transport function in maladaptive hypertrophy, these findings constitute a second important mechanism for phosphatase-dependent pathology in the hypertrophied and failing heart.
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Affiliation(s)
- Guangmao Cheng
- Gazes Cardiac Research Institute, Cardiology Division, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29403, USA
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7
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Chinnakkannu P, Samanna V, Cheng G, Ablonczy Z, Baicu CF, Bethard JR, Menick DR, Kuppuswamy D, Cooper G. Site-specific microtubule-associated protein 4 dephosphorylation causes microtubule network densification in pressure overload cardiac hypertrophy. J Biol Chem 2010; 285:21837-48. [PMID: 20436166 DOI: 10.1074/jbc.m110.120709] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In severe pressure overload-induced cardiac hypertrophy, a dense, stabilized microtubule network forms that interferes with cardiocyte contraction and microtubule-based transport. This is associated with persistent transcriptional up-regulation of cardiac alpha- and beta-tubulin and microtubule-stabilizing microtubule-associated protein 4 (MAP4). There is also extensive microtubule decoration by MAP4, suggesting greater MAP4 affinity for microtubules. Because the major determinant of this affinity is site-specific MAP4 dephosphorylation, we characterized this in hypertrophied myocardium and then assessed the functional significance of each dephosphorylation site found by mimicking it in normal cardiocytes. We first isolated MAP4 from normal and pressure overload-hypertrophied feline myocardium; volume-overloaded myocardium, which has an equal degree and duration of hypertrophy but normal functional and cytoskeletal properties, served as a control for any nonspecific growth-related effects. After cloning cDNA-encoding feline MAP4 and obtaining its deduced amino acid sequence, we characterized by mass spectrometry any site-specific MAP4 dephosphorylation. Solely in pressure overload-hypertrophied myocardium, we identified striking MAP4 dephosphorylation at Ser-472 in the MAP4 N-terminal projection domain and at Ser-924 and Ser-1056 in the assembly-promoting region of the C-terminal microtubule-binding domain. Site-directed mutagenesis of MAP4 cDNA was then used to switch each serine to non-phosphorylatable alanine. Wild-type and mutated cDNAs were used to construct adenoviruses; microtubule network density, stability, and MAP4 decoration were assessed in normal cardiocytes following an equivalent level of MAP4 expression. The Ser-924 --> Ala MAP4 mutant produced a microtubule phenotype indistinguishable from that seen in pressure overload hypertrophy, such that Ser-924 MAP4 dephosphorylation during pressure overload hypertrophy may be central to this cytoskeletal abnormality.
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Affiliation(s)
- Panneerselvam Chinnakkannu
- Cardiology Division, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina 29403, USA
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8
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Wong YY, Handoko ML, Mouchaers KTB, de Man FS, Vonk-Noordegraaf A, van der Laarse WJ. Reduced mechanical efficiency of rat papillary muscle related to degree of hypertrophy of cardiomyocytes. Am J Physiol Heart Circ Physiol 2010; 298:H1190-7. [PMID: 20118411 DOI: 10.1152/ajpheart.00773.2009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isolated rat papillary muscles of the right ventricle were used to discover the origin of reduced myocardial efficiency in chronic heart failure. Right ventricular hypertrophy was induced by monocrotaline injection, causing pulmonary hypertension. Control (n = 7) and hypertrophied (n = 11) papillary muscles were subjected to sinusoidal length changes at 37 degrees C and 5 Hz with a peak-to-peak amplitude of 15% of the length giving maximum force (L(max)) after being stretched to 92.5% of L(max). Isometric tension at L(max) was similar in control and hypertrophied muscles. Work was assessed from the area encompassed by force-length loops. Work per loop was 0.93 +/- 0.11 and 0.84 +/- 0.11 microJ/mm(3) (means +/- SE) for control and hypertrophied muscles, respectively (P = 0.591). Suprabasal O(2) uptake per work loop was 5.7 +/- 0.7 pmol/mm(3) in control muscles and 8.7 +/- 1.7 pmol/mm(3) in hypertrophied muscles (P = 0.133). Net mechanical efficiency was calculated from the ratio of work output and suprabasal O(2) uptake. The efficiency of hypertrophied muscles was 29.1 +/- 3.7% and was smaller than in control muscles (43.7 +/- 2.2%, P = 0.016). The right ventricular cardiomyocyte cross-sectional area increased from 272 +/- 17 microm(2) in control muscles to 396 +/- 31 microm(2) in hypertrophied muscles (P < 0.003). Mechanical efficiency correlated negatively with right ventricular wall thickness and cardiomyocyte cross-sectional area [Spearman rank correlation coefficients of -0.50 (P = 0.039) and -0.53 (P = 0.024), respectively]. We conclude that efficiency decreases with increasing cardiomyocyte hypertrophy. Thus, the reduced efficiency of diseased whole hearts can be at least partly explained by reduced efficiency at the cardiomyocyte level.
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Affiliation(s)
- Yeun Ying Wong
- Dept. of Physiology, Vrije Univ. Medical Center, Amsterdam, The Netherlands
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Mani SK, Shiraishi H, Balasubramanian S, Yamane K, Chellaiah M, Cooper G, Banik N, Zile MR, Kuppuswamy D. In vivo administration of calpeptin attenuates calpain activation and cardiomyocyte loss in pressure-overloaded feline myocardium. Am J Physiol Heart Circ Physiol 2008; 295:H314-26. [PMID: 18487434 PMCID: PMC2494745 DOI: 10.1152/ajpheart.00085.2008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 05/09/2008] [Indexed: 02/06/2023]
Abstract
Calpain activation is linked to the cleavage of several cytoskeletal proteins and could be an important contributor to the loss of cardiomyocytes and contractile dysfunction during cardiac pressure overload (PO). Using a feline right ventricular (RV) PO model, we analyzed calpain activation during the early compensatory period of cardiac hypertrophy. Calpain enrichment and its increased activity with a reduced calpastatin level were observed in 24- to 48-h-PO myocardium, and these changes returned to basal level by 1 wk of PO. Histochemical studies in 24-h-PO myocardium revealed the presence of TdT-mediated dUTP nick-end label (TUNEL)-positive cardiomyocytes, which exhibited enrichment of calpain and gelsolin. Biochemical studies showed an increase in histone H2B phosphorylation and cytoskeletal binding and cleavage of gelsolin, which indicate programmed cardiomyocyte cell death. To test whether calpain inhibition could prevent these changes, we administered calpeptin (0.6 mg/kg iv) by bolus injections twice, 15 min before and 6 h after induction of 24-h PO. Calpeptin blocked the following PO-induced changes: calpain enrichment and activation, decreased calpastatin level, caspase-3 activation, enrichment and cleavage of gelsolin, TUNEL staining, and histone H2B phosphorylation. Although similar administration of a caspase inhibitor, N-benzoylcarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VD-fmk), blocked caspase-3 activation, it did not alleviate other aforementioned changes. These results indicate that biochemical markers of cardiomyocyte cell death, such as sarcomeric disarray, gelsolin cleavage, and TUNEL-positive nuclei, are mediated, at least in part, by calpain and that calpeptin may serve as a potential therapeutic agent to prevent cardiomyocyte loss and preserve myocardial structure and function during cardiac hypertrophy.
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Affiliation(s)
- Santhosh K Mani
- Gazes Cardiac Research Institute, Charleston, SC 29425-2221, USA
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10
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Willey CD, Palanisamy AP, Johnston RK, Mani SK, Shiraishi H, Tuxworth WJ, Zile MR, Balasubramanian S, Kuppuswamy D. STAT3 activation in pressure-overloaded feline myocardium: role for integrins and the tyrosine kinase BMX. Int J Biol Sci 2008; 4:184-99. [PMID: 18612371 PMCID: PMC2443357 DOI: 10.7150/ijbs.4.184] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Accepted: 06/24/2008] [Indexed: 11/23/2022] Open
Abstract
Growth, survival and cytoskeletal rearrangement of cardiomyocytes are critical for cardiac hypertrophy. Signal transducer and activator of transcription-3 (STAT3) activation is an important cardioprotective factor associated with cardiac hypertrophy. Although STAT3 activation has been reported via signaling through Janus Kinase 2 (JAK2) in several cardiac models of hypertrophy, the importance of other nonreceptor tyrosine kinases (NTKs) has not been explored. Utilizing an in vivo feline right ventricular pressure-overload (RVPO) model of hypertrophy, we demonstrate that in 48 h pressure-overload (PO) myocardium, STAT3 becomes phosphorylated and redistributed to detergent-insoluble fractions with no accompanying JAK2 activation. PO also caused increased levels of phosphorylated STAT3 in both cytoplasmic and nuclear fractions. To investigate the role of other NTKs, we used our established in vitro cell culture model of hypertrophy where adult feline cardiomyocytes are embedded three-dimensionally (3D) in type-I collagen and stimulated with an integrin binding peptide containing an Arg-Gly-Asp (RGD) motif that we have previously shown to recapitulate the focal adhesion complex (FAC) formation of 48 h RVPO. RGD stimulation of adult cardiomyocytes in vitro caused both STAT3 redistribution and activation that were accompanied by the activation and redistribution of c-Src and the TEC family kinase, BMX, but not JAK2. However, infection with dominant negative c-Src adenovirus was unable to block RGD-stimulated changes on either STAT3 or BMX. Further analysis in vivo in 48 h PO myocardium showed the presence of both STAT3 and BMX in the detergent-insoluble fraction with their complex formation and phosphorylation. Therefore, these studies indicate a novel mechanism of BMX-mediated STAT3 activation within a PO model of cardiac hypertrophy that might contribute to cardiomyocyte growth and survival.
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Affiliation(s)
- Christopher D Willey
- Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, SC 29425-2221, USA
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Sakata S, Lebeche D, Sakata N, Sakata Y, Chemaly ER, Liang LF, Tsuji T, Takewa Y, del Monte F, Peluso R, Zsebo K, Jeong D, Park WJ, Kawase Y, Hajjar RJ. Restoration of mechanical and energetic function in failing aortic-banded rat hearts by gene transfer of calcium cycling proteins. J Mol Cell Cardiol 2007; 42:852-61. [PMID: 17300800 PMCID: PMC1945057 DOI: 10.1016/j.yjmcc.2007.01.003] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2006] [Revised: 12/30/2006] [Accepted: 01/03/2007] [Indexed: 10/23/2022]
Abstract
The aim of this study was to examine whether short- and long-term gene transfer of Ca(2+) handling proteins restore left ventricular (LV) mechanoenergetics in aortic banding-induced failing hearts. Aortic-banded rats received recombinant adenoviruses carrying sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a) (Banding+SERCA), parvalbumin (Banding+Parv) or beta-galactosidase (Banding+betagal), or an adeno-associated virus carrying SERCA2a (Banding+AAV.SERCA) by a catheter-based technique. LV mechanoenergetic function was measured in cross-circulated hearts. "Banding", "Banding+betagal" and "Banding+saline" groups showed lower end-systolic pressure at 0.1 ml intraballoon water (ESP(0.1)), higher end-diastolic pressure at 0.1 ml intraballoon water (EDP(0.1)) and slower LV relaxation rate, compared with "Normal" and "Sham". However, "Banding+SERCA" and "Banding+Parv" showed high ESP(0.1), low EDP(0.1) and fast LV relaxation rate. In "Banding", "Banding+betagal" and "Banding+saline", slope of relation between cardiac oxygen consumption and systolic pressure-volume area, O(2) cost of total mechanical energy, was twice higher than normal value, whereas slope in "Baning+SERCA" and "Banding+Parv" was similar to normal value. Furthermore, O(2) cost of LV contractility in the 3 control banding groups was approximately 3 times higher than normal value, whereas O(2) cost of contractility in "Banding+SERCA", "Banding+AAV.SERCA" and "Banding+Parv" was as low as normal value. Thus, high O(2) costs of total mechanical energy and of LV contractility in failing hearts indicate energy wasting both in chemomechanical energy transduction and in calcium handling. Improved calcium handling by both short- and long-term overexpression of SERCA2a and parvalbumin transforms the inefficient energy utilization into a more efficient state. Therefore enhancement of calcium handling either by resequestration into the SR or by intracellular buffering improves not only mechanical but energetic function in failing hearts.
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Affiliation(s)
- Susumu Sakata
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02114, USA
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Cooper G. Cytoskeletal networks and the regulation of cardiac contractility: microtubules, hypertrophy, and cardiac dysfunction. Am J Physiol Heart Circ Physiol 2006; 291:H1003-14. [PMID: 16679401 DOI: 10.1152/ajpheart.00132.2006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cytoskeleton as classically defined for eukaryotic cells consists of three systems of protein filaments: the microtubules, the intermediate filaments, and the microfilaments. In mature striated muscle such as the heart of the adult mammal, these three types of cytoskeletal filaments are superimposed spatially on the myofilaments, a specialized system of contractile protein filaments. Each of these systems of protein filaments has the potential to respond in an adaptive or maladaptive manner during load-induced hypertrophic cardiac growth. However, the extent to which such hypertrophy is compensatory is also critically dependent on the type of hemodynamic overload that serves as the hypertrophic stimulus. Thus cardiac hypertrophy is not intrinsically maladaptive; rather, it is the nature of the inducing load rather than hypertrophy itself that is responsible, through effects on structural and/or regulatory proteins, for the frequent deterioration of initially compensatory hypertrophy into the congestive heart failure state. As one example reviewed here of this load specificity of maladaptation, increased microtubule network density is a persistent feature of severely pressure-overloaded, hypertrophied, and failing myocardium that imposes a primarily viscous load on active myofilaments during contraction.
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Affiliation(s)
- George Cooper
- Gazes Cardiac Research Institute, Cardiology Division, PO Box 250773, Medical University of South Carolina, and Department of Veterans Affairs Medical Center, Charleston, SC 29403, USA.
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Abstract
The Frank-Starling mechanism, by which load directly regulates muscle length and thus performance is the means by which the mechanics and energetics of cardiac muscle are regulated on a beat-to-beat basis. When this short-term compensation for increased load is insufficient, the long-term compensation of cardiac hypertrophy ensues. The simplest and most direct mechanism for load regulation of cardiac mass would obtain if an analog of the short-term Frank-Starling mechanism of functional regulation operated in the long-term time domain of mass regulation; that is, if heart muscle were able to directly transduce increased load into growth. It is now clear that load does indeed serve as a direct regulator of cardiac mass in the adult. Cardiac hypertrophy, at the levels of intact animal, isolated tissue, and cultured cells, is a direct response of the adult mammalian cardiocyte to increased load, modified by but without the requisite involvement of factors external to the cell. The extent to which such hypertrophy is compensatory is critically dependent on the type of hemodynamic overload that serves as the hypertrophic stimulus. Thus, cardiac hypertrophy is not intrinsically maladaptive; rather, it is the nature of the inducing load rather than hypertrophy itself that is responsible for the frequent deterioration of initially compensatory hypertrophy into the congestive heart failure state. As one example reviewed here of this load specificity of maladaptation, increased microtubule network density is a persistent feature of severely pressure overloaded, hypertrophied and failing myocardium which imposes a viscous load on active myofilaments during contraction.
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Affiliation(s)
- G Cooper
- Gazes Cardiac Research Institute, Medical University of South Carolina, Department of Veterans Affairs Medical Center, Charleston 29403, USA.
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14
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Ishibashi Y, Takahashi M, Isomatsu Y, Qiao F, Iijima Y, Shiraishi H, Simsic JM, Baicu CF, Robbins J, Zile MR, Cooper G. Role of microtubules versus myosin heavy chain isoforms in contractile dysfunction of hypertrophied murine cardiocytes. Am J Physiol Heart Circ Physiol 2003; 285:H1270-85. [PMID: 12750067 DOI: 10.1152/ajpheart.00654.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In large mammals there is a correlation between microtubule network densification and contractile dysfunction in severe pressure-overload hypertrophy. In small mammals there is a similar correlation for the shift to beta-myosin heavy chain (MHC), a MHC isoform having a slower ATPase Vmax. In this study, murine left ventricular (LV) pressure overload invoked both mechanisms: microtubule network densification and beta-MHC expression. Cardiac beta-MHC was also augmented without altering tubulin levels by two load-independent means, chemical thyroidectomy and transgenesis. In hypertrophy, contractile function of the LV and its cardiocytes decreased proportionally; microtubule depolymerization restored normal cellular contraction. In hypothyroid mice having a complete shift from alpha-MHC to beta-MHC, contractile function of the LV and its cardiocytes also decreased, but microtubule depolymerization had no effect on cellular contraction. In transgenic mice having a cardiac beta-MHC increase similar to that in hypertrophy, contractile function of the LV and its cardiocytes was normal, and microtubule depolymerization had no effect. Thus, although both mechanisms may cause contractile dysfunction, for the extent of MHC isoform switching seen even in severe murine LV pressure-overload hypertrophy, microtubule network densification appears to have the more important role.
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Affiliation(s)
- Yuji Ishibashi
- Gazes Cardiac Research Institute, Cardiology Division, Medical University of South Carolina, 114 Doughty Street, Charleston, SC 29403, USA
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15
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Bing OHL, Conrad CH, Boluyt MO, Robinson KG, Brooks WW. Studies of prevention, treatment and mechanisms of heart failure in the aging spontaneously hypertensive rat. Heart Fail Rev 2002; 7:71-88. [PMID: 11790924 DOI: 10.1023/a:1013753907135] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The spontaneously hypertensive rat (SHR) is an animal model of genetic hypertension which develops heart failure with aging, similar to man. The consistent pattern of a long period of stable hypertrophy followed by a transition to failure provides a useful model to study mechanisms of heart failure with aging and test treatments at differing phases of the disease process. The transition from compensated hypertrophy to failure is accompanied by changes in cardiac function which are associated with altered active and passive mechanical properties of myocardial tissue; these events define the physiologic basis for cardiac decompensation. In examining the mechanism for myocardial tissue dysfunction, studies have demonstrated a central role for neurohormonal activation, and specifically the renin-angiotensin-aldosterone system. Pharmacologic attenuation of this system at differing points in the course of the process suggests that prevention but not reversal of myocardial tissue dysfunction is possible. The roles of the extracellular matrix, apoptosis, intracellular calcium, beta-adrenergic stimulation, microtubules, and oxygen supply-demand relationships in ultimately mediating myocardial tissue dysfunction are reviewed. Studies suggest that while considerable progress has been made in understanding and treating the transition to failure, our current state of knowledge is limited in scope and we are not yet able to define specific mechanisms responsible for tissue dysfunction. It will be necessary to integrate information on the roles of newly discovered, and as yet undiscovered, genes and pathways to provide a clearer understanding of maladaptive remodeling seen with heart failure. Understanding the mechanism for tissue dysfunction is likely to result in more effective treatments for the prevention and reversal of heart failure with aging. It is anticipated that the SHR model will assist us in reaching these important goals.
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Affiliation(s)
- Oscar H L Bing
- The Department of Medicine, VA Boston Healthcare System, 150 South Huntington Avenue, Boston, MA 02130, USA.
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16
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Leeuwenburgh BP, Helbing WA, Steendijk P, Schoof PH, Baan J. Biventricular systolic function in young lambs subject to chronic systemic right ventricular pressure overload. Am J Physiol Heart Circ Physiol 2001; 281:H2697-704. [PMID: 11709439 DOI: 10.1152/ajpheart.2001.281.6.h2697] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In various clinical situations of congenital heart disease, the right ventricle (RV) is subject to a chronic systemic pressure overload which affects biventricular function and may progress to the development of RV failure. Young lambs (2-3 wk old) underwent adjustable pulmonary artery banding (PAB) at systemic (aortic) level for 8 wk. Biventricular function was determined by using load-independent indexes of global ventricular contractile performance by the end-systolic pressure-volume relationship (ESPVR) using the conductance catheter at baseline and during dobutamine infusion. PAB resulted in a significant fivefold increase in RV end-systolic pressure (12-64 mmHg) and a doubling of the RV-to-left ventricular (LV) wall thickness ratio (P < 0.01). RV global contractile performance increased significantly, as indicated by an increased slope of the ESPVR. Compared with age-matched control lambs, cardiac output decreased from 2.6 to 1.6 l/min (P < 0.05) whereas heart rates were equal. In contrast with RV volume, LV volume decreased significantly after PAB (P < 0.01), whereas the LV-ESPVR slope was unchanged. In the PAB group, the RV, but not the LV, showed a reduced response to dobutamine. We concluded that chronic RV pressure overload for 8 wk results in diminished pump function despite compensatory increased RV global contractile performance.
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Affiliation(s)
- B P Leeuwenburgh
- Division of Pediatric Cardiology, Department of Pediatrics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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17
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Laser M, Willey CD, Jiang W, Cooper G, Menick DR, Zile MR, Kuppuswamy D. Integrin activation and focal complex formation in cardiac hypertrophy. J Biol Chem 2000; 275:35624-30. [PMID: 10958798 DOI: 10.1074/jbc.m006124200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.
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Affiliation(s)
- M Laser
- Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina and the Ralph H. Johnson Department of Veterans Affairs MedicalCenter, Charleston 29425-2221, USA
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18
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Sadamatsu K, Urabe Y, Tsutsui H, Tagawa H, Maruoka F, Igarashi-Saito K, Takeda K, Kawachi Y, Yasui H, Takeshita A. Sarcoplasmic reticulum Ca2+ regulatory protein gene expression in human right atrium under hemodynamic overload. Heart Vessels 2000; 14:208-15. [PMID: 10830916 DOI: 10.1007/bf01747849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Sarcoplasmic reticulum (SR) Ca2+-adenosine triphosphatase (ATPase) mRNA expression is reduced in the failing human myocardium. However, it is not known whether SR Ca2+-regulatory protein gene expression is altered in human myocardial tissue subjected to pressure overload or volume overload. We sought to determine whether SR Ca2+-regulatory protein gene expression is altered in human atrial tissue subjected to mechanical overload. We obtained right atrial myocardial tissue (about 250mg) at open-heart surgery from three groups of patients: no hemodynamic overload to the right atrium (control group; 12 patients), atrial septal defect (ASD group; 8 patients), and tricuspid regurgitation (TR group; 7 patients). We measured the myocyte size, the area of interstitial fibrosis, SR Ca2+,-ATPase, and ryanodine receptor mRNA abundance. The isolated cardiocyte area and the percent area of interstitial fibrosis were in the order TR > ASD > control (P < 0.05). The SR Ca2+-ATPase mRNA level in TR was significantly decreased (P = 0.004) compared with the control, whereas in the ASD group it did not differ significantly from control. There were no significant differences in ryanodine receptor mRNA levels among the three groups. SR Ca2+-ATPase gene expression was downregulated in human atrial tissue with TR but not in ASD, which might have resulted from the differences in the degree and/or the type of hemodynamic overload to the myocardium.
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Affiliation(s)
- K Sadamatsu
- Research Institute of Angiocardiology, Cardiovascular Clinic, Faculty of Medicine, Kyushu University School of Medicine, Fukuoka, Japan
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19
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Narishige T, Blade KL, Ishibashi Y, Nagai T, Hamawaki M, Menick DR, Kuppuswamy D, Cooper G. Cardiac hypertrophic and developmental regulation of the beta-tubulin multigene family. J Biol Chem 1999; 274:9692-7. [PMID: 10092657 DOI: 10.1074/jbc.274.14.9692] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Increased microtubule density, through viscous loading of active myofilaments, causes contractile dysfunction of hypertrophied and failing pressure-overloaded myocardium, which is normalized by microtubule depolymerization. We have found this to be based on augmented tubulin synthesis and microtubule stability. We show here that increased tubulin synthesis is accounted for by marked transcriptional up-regulation of the beta1- and beta2-tubulin isoforms, that hypertrophic regulation of these genes recapitulates their developmental regulation, and that the greater proportion of beta1-tubulin protein may have a causative role in the microtubule stabilization found in cardiac hypertrophy.
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Affiliation(s)
- T Narishige
- Gazes Cardiac Research Institute, Cardiology Division of the Department of Medicine, Medical University of South Carolina, Veterans Affairs Medical Center, Charleston, South Carolina 29403, USA
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20
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Koide M, Carabello BA, Conrad CC, Buckley JM, DeFreyte G, Barnes M, Tomanek RJ, Wei CC, Dell'Italia LJ, Cooper G, Zile MR. Hypertrophic response to hemodynamic overload: role of load vs. renin-angiotensin system activation. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H350-8. [PMID: 9950833 DOI: 10.1152/ajpheart.1999.276.2.h350] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myocardial hypertrophy is one of the basic mechanisms by which the heart compensates for hemodynamic overload. The mechanisms by which hemodynamic overload is transduced by the cardiac muscle cell and translated into cardiac hypertrophy are not completely understood. Candidates include activation of the renin-angiotensin system (RAS) and angiotensin II receptor (AT1) stimulation. In this study, we tested the hypothesis that load, independent of the RAS, is sufficient to stimulate cardiac growth. Four groups of cats were studied: 14 normal controls, 20 pulmonary artery-banded (PAB) cats, 7 PAB cats in whom the AT1 was concomitantly and continuously blocked with losartan, and 8 PAB cats in whom the angiotensin-converting enzyme (ACE) was concomitantly and continuously blocked with captopril. Losartan cats had at least a one-log order increase in the ED50 of the blood pressure response to angiotensin II infusion. Right ventricular (RV) hypertrophy was assessed using the RV mass-to-body weight ratio and ventricular cardiocyte size. RV hemodynamic overload was assessed by measuring RV systolic and diastolic pressures. Neither the extent of RV pressure overload nor RV hypertrophy that resulted from PAB was affected by AT1 blockade with losartan or ACE inhibition with captopril. RV systolic pressure was increased from 21 +/- 3 mmHg in normals to 68 +/- 4 mmHg in PAB, 65 +/- 5 mmHg in PAB plus losartan and 62 +/- 3 mmHg in PAB plus captopril. RV-to-body weight ratio increased from 0.52 +/- 0.04 g/kg in normals to 1.11 +/- 0.06 g/kg in PAB, 1.06 +/- 0.06 g/kg in PAB plus losartan and 1.06 +/- 0.06 g/kg in PAB plus captopril. Thus 1) pharmacological modulation of the RAS with losartan and captopril did not change the extent of the hemodynamic overload or the hypertrophic response induced by PAB; 2) neither RAS activation nor angiotensin II receptor stimulation is an obligatory and necessary component of the signaling pathway that acts as an intermediary coupling load to the hypertrophic response; and 3) load, independent of the RAS, is capable of stimulating cardiac growth.
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Affiliation(s)
- M Koide
- Cardiology Section, Department of Medicine and Physiology, Gazes Cardiac Research Institute, Medical University of South Carolina, Veterans Affairs Medical Center, Charleston, South Carolina 29401, USA
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21
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Zile MR, Koide M, Sato H, Ishiguro Y, Conrad CH, Buckley JM, Morgan JP, Cooper G. Role of microtubules in the contractile dysfunction of hypertrophied myocardium. J Am Coll Cardiol 1999; 33:250-60. [PMID: 9935038 DOI: 10.1016/s0735-1097(98)00550-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVES We sought to determine whether the ameliorative effects of microtubule depolymerization on cellular contractile dysfunction in pressure overload cardiac hypertrophy apply at the tissue level. BACKGROUND A selective and persistent increase in microtubule density causes decreased contractile function of cardiocytes from cats with hypertrophy produced by chronic right ventricular (RV) pressure overloading. Microtubule depolymerization by colchicine normalizes contractility in these isolated cardiocytes. However, whether these changes in cellular function might contribute to changes in function at the more highly integrated and complex cardiac tissue level was unknown. METHODS Accordingly, RV papillary muscles were isolated from 25 cats with RV pressure overload hypertrophy induced by pulmonary artery banding (PAB) for 4 weeks and 25 control cats. Contractile state was measured using physiologically sequenced contractions before and 90 min after treatment with 10(-5) mol/liter colchicine. RESULTS The PAB significantly increased RV systolic pressure and the RV weight/body weight ratio in PAB; it significantly decreased developed tension from 59+/-3 mN/mm2 in control to 25+/-4 mN/mm2 in PAB, shortening extent from 0.21+/-0.01 muscle lengths (ML) in control to 0.12+/-0.01 ML in PAB, and shortening rate from 1.12+/-0.07 ML/s in control to 0.55+/-0.03 ML/s in PAB. Indirect immunofluorescence confocal microscopy showed that PAB muscles had a selective increase in microtubule density and that colchicine caused complete microtubule depolymerization in both control and PAB papillary muscles. Microtubule depolymerization normalized myocardial contractility in papillary muscles of PAB cats but did not alter contractility in control muscles. CONCLUSIONS Excess microtubule density, therefore, is equally important to both cellular and to myocardial contractile dysfunction caused by chronic, severe pressure-overload cardiac hypertrophy.
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Affiliation(s)
- M R Zile
- Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Veterans Administration Medical Center, Charleston 29425-5799, USA.
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22
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Abstract
This article takes three different approaches to the question of whether the failing heart is in an energy-starved state. A brief historical overview introduces the issue and points out problems in both models and methods. Second, current information regarding the energetic state of the failing heart is examined. Finally, the mechanistic and therapeutic implications of a defect in energy production are described.
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Affiliation(s)
- A M Katz
- Department of Medicine, University of Connecticut School of Medicine, Farmington, USA.
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23
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Sato H, Nagai T, Kuppuswamy D, Narishige T, Koide M, Menick DR, Cooper G. Microtubule stabilization in pressure overload cardiac hypertrophy. J Cell Biol 1997; 139:963-73. [PMID: 9362514 PMCID: PMC2139973 DOI: 10.1083/jcb.139.4.963] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/1997] [Revised: 10/10/1997] [Indexed: 02/05/2023] Open
Abstract
Increased microtubule density, for which microtubule stabilization is one potential mechanism, causes contractile dysfunction in cardiac hypertrophy. After microtubule assembly, alpha-tubulin undergoes two, likely sequential, time-dependent posttranslational changes: reversible carboxy-terminal detyrosination (Tyr-tubulin left and right arrow Glu-tubulin) and then irreversible deglutamination (Glu-tubulin --> Delta2-tubulin), such that Glu- and Delta2-tubulin are markers for long-lived, stable microtubules. Therefore, we generated antibodies for Tyr-, Glu-, and Delta2-tubulin and used them for staining of right and left ventricular cardiocytes from control cats and cats with right ventricular hypertrophy. Tyr- tubulin microtubule staining was equal in right and left ventricular cardiocytes of control cats, but Glu-tubulin and Delta2-tubulin staining were insignificant, i.e., the microtubules were labile. However, Glu- and Delta2-tubulin were conspicuous in microtubules of right ventricular cardiocytes from pressure overloaded cats, i.e., the microtubules were stable. This finding was confirmed in terms of increased microtubule drug and cold stability in the hypertrophied cells. In further studies, we found an increase in a microtubule binding protein, microtubule-associated protein 4, on both mRNA and protein levels in pressure-hypertrophied myocardium. Thus, microtubule stabilization, likely facilitated by binding of a microtubule-associated protein, may be a mechanism for the increased microtubule density characteristic of pressure overload cardiac hypertrophy.
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Affiliation(s)
- H Sato
- Cardiology Section of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina 29401, USA
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24
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Kuppuswamy D, Kerr C, Narishige T, Kasi VS, Menick DR, Cooper G. Association of tyrosine-phosphorylated c-Src with the cytoskeleton of hypertrophying myocardium. J Biol Chem 1997; 272:4500-8. [PMID: 9020175 DOI: 10.1074/jbc.272.7.4500] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Given the central position of the focal adhesion complex, both physically in coupling integrins to the interstitium and biochemically in providing an upstream site for anabolic signal generation, we asked whether the recruitment of non-receptor tyrosine kinases to the cytoskeleton might be a mechanism whereby cellular loading could activate growth regulatory signals responsible for cardiac hypertrophy. Analysis revealed cytoskeletal association of c-Src, FAK, and beta3-integrin, but no Fyn, in the pressure-overloaded right ventricle. This association was seen as early as 4 h after right ventricular pressure overloading, increased through 48 h, and reverted to normal in 1 week. Cytoskeletal binding of non-receptor tyrosine kinases was synchronous with tyrosine phosphorylation of several cytoskeletal proteins, including c-Src. Examination of cytoskeleton-bound c-Src revealed that a significant portion of the tyrosine phosphorylation was not at the Tyr-527 site and therefore presumably was at the Tyr-416 site. Thus, these studies strongly suggest that non-receptor tyrosine kinases, in particular c-Src, may play a critical role in hypertrophic growth regulation by their association with cytoskeletal structures, possibly via load activation of integrin-mediated signaling.
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Affiliation(s)
- D Kuppuswamy
- Department of Cell Biology, Gazes Cardiac Research Institute and Veterans Administration Hospital, Medical University of South Carolina, Charleston, South Carolina 29425-2221, USA
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25
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26
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Janati-Idrissi R, Besson B, Laplace M, Bui MH. In situ mitochondrial function in volume overload- and pressure overload-induced cardiac hypertrophy in rats. Basic Res Cardiol 1995; 90:305-13. [PMID: 8534255 DOI: 10.1007/bf00797908] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES Little comparative information is available on mitochondrial function changes during experimentally-induced hypertrophy. Respiratory control mechanisms are not exactly the same in situ and in isolated mitochondria. This study assessed in situ mitochondrial function in two myocardial hypertrophy models. METHODS Cytochrome aa3 (Cytaa3) and myoglobin (Mb) absorption changes were monitored in isolated rat hearts using dual wavelength spectrophotometry (Cytaa3: 605-630 nm, Mb: 581-592 nm). Hypertrophy was induced by creation of an aortic stenosis or of an aorto-caval fistula. Optical monitoring was performed on diastole-arrested perfused hearts using the sequence O2 perfusion, N2 perfusion during 4 min, and reoxygenation. The plateaus of the Cytaa3 and Mb curves were used to quantify oxidation-reduction and oxygenation levels. Respiratory kinetics were characterized by the slopes of transition phase curves. RESULTS Myoglobin oxygenation was comparable in the hypertrophied and control hearts. However, Cytaa3 oxidation-reduction levels in the hypertrophied hearts showed a shift towards greater reduction in comparison with the controls (controls: 0.580 +/- 0.008 DO605/DO630 nm, n = 34; fistula: 0.530 +/- 0.023, n = 23; stenosis: 0.522 +/- 0.016, n = 20, p < 0.001). The rate of Cytaa3 reduction and the rate of myoglobin deoxygenation were significantly accelerated (p < 0.005) in the volume overload group (0.507 +/- 0.043, n = 23), whereas the respiratory rate in the pressure overload group (0.389 +/- 0.034, n = 20) was comparable to that in the control hearts (0.358 +/- 0.026 delta DO 605 nm/DO630 nm.min-1, n = 34). CONCLUSION We found mitochondrial function alterations in both volume overload- and pressure overload-induced cardiac hypertrophy, despite adequate cytosol oxygenation. The patterns of these alterations differed: the redox state showed a shift of similar magnitude toward greater reduction in both models, but the respiratory rate was increased in the volume-overloaded hearts and unchanged in the pressure-overloaded hearts. The modification in the oxidation-reduction state suggested that overload hypertrophy may induce changes in the metabolism of the myocardium, which may, in turn, load to persistent modifications in mitochondrial function. The differences between the two models suggest that adaptation to hypertrophy-inducing events exists at the level of the mitochondrion.
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27
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Dai KS, Liang CS, Ch'iu YT, Yang PC, Cheng IC. Altered adenosine triphosphatase activities in pigs with naturally occurring hypertrophic cardiomyopathy. Vet Res Commun 1995; 19:115-25. [PMID: 7645194 DOI: 10.1007/bf01839277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The purpose of this study was to determine whether myocardial adenosine triphosphatase (ATPase) activities were reduced in pigs with naturally occurring hypertrophic cardiomyopathy (HCM). The selection of hearts for the HCM and the normal control groups depended on histological examination. Specific ATPase activity and 5'-nucleotidase activity were measured in left ventricular myocardium obtained from HCM (n = 7) and normal control (n = 7) animals. The histological features of HCM included marked disorientation of muscle cells, thickening of the intramural coronary arterial wall with a narrowed lumen, endocardial fibrosis and myocardial fibrosis. The HCM group showed significant increases in both heart weight (32%) and heart weight to body weight ratio (46%). The total ATPase activity in crude homogenates from the HCM group was significantly decreased by 16%. Azide-sensitive ATPase (mitochondrial ATPase) activity, ouabain-sensitive ATPase (Na+, K+-ATPase) activity, basal Mg(2+)-ATPase activity and Ca(2+)-ATPase activity were all significantly decreased by 18%, 30%, 20% and 50%, respectively. In contrast, no significant decrease was found in the mean values for 5'-nucleotidase activity. These results suggest that myocardial ATPase activities are suppressed in pigs with naturally occurring HCM.
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Affiliation(s)
- K S Dai
- Department of Comparative Medicine, Pig Research Institute Taiwan, R.O.C
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28
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Tsutsui H, Ishihara K, Cooper G. Cytoskeletal role in the contractile dysfunction of hypertrophied myocardium. Science 1993; 260:682-7. [PMID: 8097594 DOI: 10.1126/science.8097594] [Citation(s) in RCA: 204] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cardiac hypertrophy in response to systolic pressure loading frequently results in contractile dysfunction of unknown cause. In the present study, pressure loading increased the microtubule component of the cardiac muscle cell cytoskeleton, which was responsible for the cellular contractile dysfunction observed. The linked microtubule and contractile abnormalities were persistent and thus may have significance for the deterioration of initially compensatory cardiac hypertrophy into congestive heart failure.
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Affiliation(s)
- H Tsutsui
- Department of Medicine, Medical University of South Carolina, Charleston
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29
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Brooks WW, Healey NA, Sen S, Conrad CH, Bing OH. Oxygen cost of stress development in hypertrophied and failing hearts from the spontaneously hypertensive rat. Hypertension 1993; 21:56-64. [PMID: 8418024 DOI: 10.1161/01.hyp.21.1.56] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Left ventricular isovolumic stress development and metabolic parameters were studied in 18-24-month-old spontaneously hypertensive rats (SHRs) and age-matched Wistar-Kyoto (WKY) rat controls using the isolated, isovolumic (balloon in left ventricle) buffer-perfused rat heart preparation. After WKY rats and all SHRs were compared, SHRs were divided into two groups: those animals with (SHR-F) and without (SHR-NF) evidence of heart failure. Hearts were perfused at 100 mm Hg using a constant pressure system at a temperature of 37 degrees C. In the baseline state, peak systolic pressure was greatest in the SHR-NF group and lowest in the SHR-F group. Peak midwall stress was greatest in the WKY group and, again, lowest in the SHR-F group. Oxygen consumption was lowest in the SHR-F group. When the oxygen cost of stress development was estimated by normalizing myocardial oxygen consumption by peak developed midwall stress, values were lowest in the WKY, greater in the SHR-NF, and greatest in the SHR-F group. Lactate production did not occur in the baseline state in any of the groups. Functional and metabolic responses to graded hypoxia, induced by changing the gas mixture of the perfusate from 95% to 50%, 25%, and 0% oxygen at perfusion pressures of 100 and 130 mm Hg, were studied. Increasing perfusion pressure generally resulted in small increases in peak systolic pressure and myocardial oxygen consumption but did not substantially reverse the contractile or metabolic deficit present in the SHR-F group.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W W Brooks
- Medical Service, Boston VA Medical Center, MA 02130
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Kiriazis H, Gibbs CL, Kotsanas G, Young IR. Mechanical and energetic changes in short-term volume and pressure overload of rabbit heart. Heart Vessels 1992; 7:175-88. [PMID: 1487456 DOI: 10.1007/bf01744602] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The mechanical and energetic consequences of a short-term volume overload (STVOL) hypertrophy and short-term pressure overload (STPOL) hypertrophy have been investigated in rabbits and compared with short-term sham-operated controls (STSOC). Hypertrophy was induced either by creating an aortocaval shunt (volume overload) or by banding the pulmonary artery (pressure overload). Suitable papillary muscles were excised from the hearts 8-10 days after the surgical procedure. At 27 degrees C and a stimulus frequency of 1.0 Hz, peak stress development of the STVOL preparations was significantly reduced from the control group, whereas no significant difference in peak stress development was evident between the STPOL and STSOC groups. Surprisingly, the STPOL preparations displayed pulsus alternans after only 8-10 days of inducing the overload. At steady-state conditions, the isometric 10%-90% rise times, the 90%-10% relaxation times, and the 1/2-widths were not significantly different between the treated and control groups. In isotonically contracting muscles working against a range of afterloads, the enthalpy (energy) and work output of the STVOL and STPOL preparations were depressed compared to the STSOC preparations; the differences were statistically significant for the STVOL group. Due to the parallel change in work and enthalpy, the mechanical efficiency was unaltered. A force-length-area (FLA) analysis, analogue of the pressure-volume-area (PVA) analysis, was applied to the isotonic data of this study. The isotonic enthalpy at the various load levels was plotted against the measured FLA and the data were fitted by linear regression. It was evident that the FLA correlated closely with the energy used. The STVOL and STPOL mean total energy:FLA regression lines lay parallel to but were below the STSOC line, signifying a drop in the activation heat, although this reduction did not achieve statistical significance. It is concluded that significant mechanical and energetic changes are evident after a short-term volume overload although earlier work has shown that these differences are absent at the later, compensated stage of hypertrophy. Changes associated with the pressure overload model suggest a disturbance in calcium regulation: this effect is also seen in long-term pressure overload.
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Affiliation(s)
- H Kiriazis
- Department of Physiology, Monash University, Clayton, Australia
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Osbakken M, Douglas PS, Ivanics T, Zhang DN, Van Winkle T. Creatinine kinase kinetics studied by phosphorus-31 nuclear magnetic resonance in a canine model of chronic hypertension-induced cardiac hypertrophy. J Am Coll Cardiol 1992; 19:223-8. [PMID: 1530854 DOI: 10.1016/0735-1097(92)90076-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To determine whether cardiac hypertrophy secondary to chronic renovascular hypertension is associated with altered in vivo myocardial metabolism, phosphorus-31 nuclear magnetic resonance saturation transfer techniques were used to study creatine kinase (CK) kinetics in six chronically hypertensive dogs with moderate cardiac hypertrophy and eight control dogs. The forward rate constant of CK and the flux of phosphocreatine to adenosine triphosphate were determined in both groups of dogs before and during norepinephrine administration (1 microgram/kg per min), used to increase heart rate x systolic blood pressure (rate-pressure product), cardiac output and oxygen consumption. Baseline and norepinephrine-induced changes in rate-pressure product, cardiac output and oxygen consumption were similar in both groups of dogs, as were baseline forward rate constant and flux of phosphocreatine to adenosine triphosphate. However, the norepinephrine-induced changes in forward rate constant and flux were significantly less in hypertensive than in control dogs (p less than 0.05) even though changes in hemodynamic and functional variables were similar in both groups. These data demonstrate that moderate myocardial hypertrophy is associated with altered CK kinetics, which do not appear to affect the heart's ability for global mechanical recruitment at this stage in the hypertensive process. It is possible that the changes in myocardial enzyme kinetics may contribute to diastolic dysfunction previously reported in this model and may be a precursor for ultimate development of heart failure if hypertension is maintained for prolonged periods.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Osbakken
- Department of Medicine (Cardiology), School of Medicine, University of Pennsylvania, Philadelphia 19104
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Abstract
Knowledge of the basic alterations of central hemodynamics in congestive heart failure has failed to explain many aspects of this important syndrome. Increasing attention has recently been paid to compensatory and adaptive mechanisms occurring after the initial insult. Thus, new insights have been gained into the pathophysiology of contraction of hypertrophied myocardium and changes of adrenergic receptors in the myocardium due to chronically increased cardiac sympathetic tone. The role of the renin-angiotensin-aldosterone system in early and advanced congestive heart failure has been further elucidated, and the role of the vasodilating atrial natriuretic peptide is undergoing further definition. New results further clarify the mechanisms leading to breathlessness and muscular fatigue in congestive heart failure, with emphasis shifting from the traditional concept of the importance of increased filling pressures to changes to the peripheral circulation and exercising muscles. Although progress has been made in understanding of the pathophysiology of congestive heart failure, many aspects are still poorly understood and await clarification.
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Affiliation(s)
- F Burkart
- Division of Cardiology, University Hospital Basel, Switzerland
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Affiliation(s)
- P Anversa
- Department of Pathology, New York Medical College, Valhalla 10595
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Bache RJ, Dai XZ. Myocardial oxygen consumption during exercise in the presence of left ventricular hypertrophy secondary to supravalvular aortic stenosis. J Am Coll Cardiol 1990; 15:1157-64. [PMID: 2138185 DOI: 10.1016/0735-1097(90)90258-q] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The hypothesis that abnormally increased myocardial oxygen demands may contribute to increased vulnerability to ischemia during exercise in the chronically pressure-overloaded hypertrophied left ventricle was tested. Myocardial oxygen consumption was measured during a five stage graded treadmill exercise protocol in eight normal dogs and nine adult dogs in which a 90% increase in left ventricular mass was produced by banding the ascending aorta at 8 weeks of age. Heart rate increased progressively during exercise in both groups of dogs, but was significantly faster than normal in the group with aortic banding. Coronary blood flow increased progressively with exercise in both groups, but was significantly greater than normal in dogs with aortic banding during each exercise stage. Coronary sinus oxygen tension decreased significantly and similarly during exercise in normal and hypertrophied hearts. In dogs with hypertrophy, oxygen consumption per gram of myocardium averaged 52% greater than normal during exercise. This excess myocardial oxygen consumption in dogs with aortic banding resulted from an abnormally large increase in oxygen consumption per beat during exercise and from the faster heart rate in this group of dogs. Measurements of myocardial blood flow with microspheres demonstrated a lower subendocardial/subepicardial blood flow ratio in dogs with hypertrophy; this ratio decreased significantly during exercise in dogs with hypertrophy, but not in normal dogs. These data are consistent with the hypothesis that increased vulnerability to ischemia in the pressure-overloaded hypertrophied left ventricle is the result of both increased myocardial oxygen demands during exercise and abnormalities of myocardial perfusion.
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Affiliation(s)
- R J Bache
- Department of Medicine, University of Minnesota Medical School, Minneapolis
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Nirasawa Y, Akera T. Pressure-induced cardiac hypertrophy: changes in Na+,K+-ATPase and glycoside actions in cats. Eur J Pharmacol 1987; 137:77-83. [PMID: 3038578 DOI: 10.1016/0014-2999(87)90184-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Effects of myocardial hypertrophy caused by pressure overload on sarcolemmal Na+,K+-ATPase and positive inotropic action of strophanthidin were examined in cats. Partial ligation of the main pulmonary artery for four weeks resulted in right ventricular hypertrophy with no significant changes in left ventricular muscle. Hypertrophy was associated with a reduction in the number of active Na+,K+-ATPase units. Affinity of the remaining enzyme for [3H]ouabain was unchanged. No apparent right or left shift in dose-response curve for the positive inotropic effect of strophanthidin was observed and toxic concentrations of strophanthidin were unchanged; however, the degree of the positive inotropic effect produced by high concentrations of strophanthidin was significantly smaller in hypertrophied muscle. Moreover, decreases in developed tension rather than tachyarrhythmias was the predominant form of toxicity observed in hypertrophied muscle. These results indicate that myocardial hypertrophy reduces the number of active Na+,K+-ATPase units per milligram protein, decreases maximal positive inotropic effect of strophanthidin, and alters the prevailing form of strophanthidin toxicity.
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Lauva IK, Brody E, Tiger E, Kent RL, Copper G, Marino TA. Control of myocardial tissue components and cardiocyte organelles in pressure-overload hypertrophy of the cat right ventricle. THE AMERICAN JOURNAL OF ANATOMY 1986; 177:71-80. [PMID: 2877565 DOI: 10.1002/aja.1001770109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Previous studies have demonstrated that there is a disproportionate increase in connective tissue in right ventricular myocardium subjected to pressure-overload hypertrophy associated with depressed cardiac contractility. While the myocardium is primarily responsive to load, the aim of the present study was to determine whether catecholamines also modulate the response of myocardial tissue components and cardiocyte organelles in pressure-overload-induced cardiac hypertrophy. Four experimental groups of cats were examined: a sham-operated control group, a group which had their pulmonary arteries banded in order to induce a pressure overload, a group which had been subjected to the same pressure overload, but in addition had beta-adrenoceptor blockade produced prior to and during the pressure overloading, and a group which had been subjected to the same pressure overload, but in addition had alpha-adrenoceptor blockade produced prior to and maintained during the pressure overloading. As in our previous study, there was a significant and equivalent degree of right ventricular hypertrophy in all experimental groups with pressure overload when assessed either as the ratio of right ventricular weight to body weight or as cardiocyte cross-sectional area. At the light microscopic level, the disproportionate increase in the volume density of myocardial connective tissue seen in banded animals was completely prevented by either alpha- or beta-adrenoceptor blockade. At the electron microscopic level, there was a reduction in the mitochondrial and myofibrillar volume fractions following beta-adrenoceptor blockade. The results of this study provide evidence for a modulatory role of catecholamines in the control of myocardial connective-tissue proliferation in pressure-overload-induced cardiac hypertrophy. There is also evidence to support the role of the adrenergic nervous system in regulating cardiocyte subcellular organelles, independent of the regulation of cardiocyte size.
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Marino TA, Brody E, Lauva IK, Kent RL, Cooper G. Reversibility of the structural effects of pressure overload hypertrophy of cat right ventricular myocardium. Anat Rec (Hoboken) 1986; 214:141-7. [PMID: 2937350 DOI: 10.1002/ar.1092140206] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The purpose of the present quantitative structural study was to determine whether the histological alterations seen in pressure overloaded myocardium return to normal, as in vitro contractile function does, upon removal of the pressure overload stimulus. Three experimental groups of four cats each were studied: a group with pulmonary artery banding to create a pressure overload, a group that had been subjected to an equivalent duration of pressure overload and then had that pressure overload removed, and a group of sham-operated controls. Seven to 10 weeks after each operative procedure, the right ventricular pressure was elevated only in the pulmonary artery-banded group. The right ventricle/body weight ratio was significantly increased in the pressure overloaded group only. The body weight at sacrifice, the left ventricle/body weight ratio, and the right ventricular end-diastolic pressure did not differ significantly in the three groups. The striking histological changes in the right ventricular myocardium hypertrophing in response to a pressure overload were the decrease in the volume density of cardiocytes and the increase in connective tissue in papillary muscles. These were reversed when the pressure overload was removed. This study demonstrates that when a pressure overload is removed, myocardial structure returns to normal as the function returns to normal. Given the critical importance of the proportion of cardiocytes and connective tissue components to both systolic and diastolic cardiac function, these data support the hypothesis that the abnormal proportions of these structures provide a potential morphological basis for at least some of the functional abnormalities observed in pressure overload hypertrophy of the cat right ventricle.
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Cooper G, Kent RL, Uboh CE, Thompson EW, Marino TA. Hemodynamic versus adrenergic control of cat right ventricular hypertrophy. J Clin Invest 1985; 75:1403-14. [PMID: 3158672 PMCID: PMC425477 DOI: 10.1172/jci111842] [Citation(s) in RCA: 107] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The purpose of this study was to determine whether cardiac hypertrophy in response to hemodynamic overloading is a primary result of the increased load or is instead a secondary result of such other factors as concurrent sympathetic activation. To make this distinction, four experiments were done; the major experimental result, cardiac hypertrophy, was assessed in terms of ventricular mass and cardiocyte cross-sectional area. In the first experiment, the cat right ventricle was loaded differentially by pressure overloading the ventricle, while unloading a constituent papillary muscle; this model was used to ask whether any endogenous or exogenous substance caused uniform hypertrophy, or whether locally appropriate load responses caused ventricular hypertrophy with papillary muscle atrophy. The latter result obtained, both when each aspect of differential loading was simultaneous and when a previously hypertrophied papillary muscle was unloaded in a pressure overloaded right ventricle. In the second experiment, epicardial denervation and then pressure overloading was used to assess the role of local neurogenic catecholamines in the genesis of hypertrophy. The degree of hypertrophy caused by these procedures was the same as that caused by pressure overloading alone. In the third and fourth experiments, beta-adrenoceptor or alpha-adrenoceptor blockade was produced before and maintained during pressure overloading. The hypertrophic response did not differ in either case from that caused by pressure overloading without adrenoceptor blockade. These experiments demonstrate the following: first, cardiac hypertrophy is a local response to increased load, so that any factor serving as a mediator of this response must be either locally generated or selectively active only in those cardiocytes in which stress and/or strain are increased; second, catecholamines are not that mediator, in that adrenergic activation is neither necessary for nor importantly modifies the cardiac hypertrophic response to an increased hemodynamic load.
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Cardiac Hypertrophy and Altered Cellular Electrical Activity of the Myocardium. PHYSIOLOGY AND PATHOPHYSIOLOGY OF THE HEART 1984. [DOI: 10.1007/978-1-4757-1171-4_25] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Marino TA, Houser SR, Cooper G. Early morphological alterations of pressure-overloaded cat right ventricular myocardium. Anat Rec (Hoboken) 1983; 207:417-26. [PMID: 6228168 DOI: 10.1002/ar.1092070304] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Pressure overload of the right ventricle results in an increase in ventricular mass. It also results in abnormal in vitro contractile function in advance of the onset of congestive heart failure as determined in papillary muscles removed from these ventricles. To correlate these functional abnormalities with any early underlying morphological changes, a band was placed around the proximal pulmonary artery of cats. This band restricted the lumen to 20% of normal and was left in place for 2 weeks. At that time, hemodynamic variables were measured to insure that right ventricular pressure overload had been produced. The hearts were then perfusion fixed, and papillary muscles from the right ventricle were prepared for light and transmission electron microscopy. Quantitative morphological data were obtained for the volume density both of several tissue components and of several organelles. It was found that there are significant increases in myocyte cross-sectional area and diameter in hypertrophied tissue with a concurrent increase in the volume density of interstitial tissue. There are no alterations in the volume density of organelles in the hypertrophied myocytes. We suggest that the substantial increase in the proportion of connective tissue and the decrease in the surface area to volume ratio that accompany pressure overload cardiac hypertrophy may be early underlying structural changes that relate directly to the abnormal contractile function found in this type of hypertrophy.
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Abstract
It is known that children with aortic stenosis (AS) frequently have supernormal indexes of left ventricular (LV) pump function and remain compensated for many years. Factors causing this increase in pump performance have not been elucidated. A study was done on LV mechanics in 11 children with AS (aortic valve area 0.5 +/- 0.3 cm2/m2) and 10 normal subjects. The ejection fraction in the AS group (0.88 +/- 0.08) was significantly higher than in normal subjects (0.64 +/- 0.08, p less than 0.001). The mean velocity of fiber shortening was also higher in AS patients (1.80 +/- 0.35 circ/s) than in normal subjects (1.22 +/- 0.21 circ/s, p less than 0.001). The end-systolic volume index in patients with AS (9 +/- 8 ml/m2) was much lower than in normal subjects (27 +/- 8 ml/m2). LV mass in patients with AS was 180 +/- 58 g/m2 compared with 96 +/- 9 in normal subjects. LV wall stress was reduced throughout the cardiac cycle in patients with AS. Peak stress in patients with AS was 238 +/- 51 dynes/cm2 X 10(3) versus 439 +/- 85 in normal subjects. The end-systolic stress-end-systolic volume index ratio, an indicator of contractile state, was not elevated in patients with AS. It is suggested that diminished wall stress in concert with normal contractile function permits the supernormal pump function seen at rest in children with AS.
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43
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Total and Transmural Perfusion of the Hypertrophied Heart. DEVELOPMENTS IN CARDIOVASCULAR MEDICINE 1983. [DOI: 10.1007/978-94-009-6759-5_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Al-Nouri MB, Ford LE, Wix H. Dimensional correlates of left ventricular dilation in the presence of hypertrophy. Chest 1983; 83:43-9. [PMID: 6217034 DOI: 10.1378/chest.83.1.43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Twelve normal subjects, 50 patients with valvular heart disease, and 14 with hypertension were studied. Those with valvular disease were divided into two groups: 28 with angiographically measured ejection fractions greater than or equal to 0.6 and 22 with ejection fractions less than 0.6. The echocardiographically measured ventricular thickness divided by radius ratio (t/r) was approximately proportional to peak systolic pressure (P) in all groups having ejection fractions greater than or equal to 0.6, so that the t/r divided by P ratios were nearly the same. Patients with ejection fractions less than 0.6 had significantly lower t/r divided by P values. No single component of the t/r divided by P ratio would identify the patients with lower ejection fractions. The t/r divided by P ratios in 14 hypertensive patients were nearly identical to the ratios in six patients with aortic stenosis and ejection fractions greater than or equal to 0.6, indicating that an aortic valve gradient does not cause a grossly abnormal form of pressure hypertrophy. The t/r ratio is thus a double sensitive, noninvasive index of dilation when correlated with systolic pressure.
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Kissling G, Rupp H, Malloy L, Jacob R. Alterations in cardiac oxygen consumption under chronic pressure overload. Significance of the isoenzyme pattern of myosin. Basic Res Cardiol 1982; 77:255-69. [PMID: 6214250 DOI: 10.1007/bf01908041] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Hypertension and resulting left ventricular hypertrophy was induced in young male Wistar rats (60 to 70 days old) by narrowing of one renal artery (Goldblatt II). 8 and 24 weeks after operation, myocardial oxygen consumption was measured on a modified in situ heart-lung preparation with nearly isovolumetric left ventricular contractions. Measured myocardial oxygen consumption was related to left ventricular wall stress. The myosin isoenzyme pattern of each heart was determined with pyrophosphate gel electrophoresis. Oxygen consumption related to wall stress averaged over the entire heart cycle amounted to 15 mumoles O2/g X min 8 weeks after operation, and 24.4 mumoles O2/g X min in age-matched controls (delta 38%, p less than 0.0005). When wall stress was averaged over systole, oxygen consumption of the hypertrophied hearts amounted to 0.112 mumoles O2/g x beat, and 0.149 mumoles O2/g x beat in the controls (delta 25%, p less than 0.05). The proportion of VM-3 (the cardiac myosin isoenzyme of lowest ATPase activity) increased from 26.3% in the controls to 30.1% in the Goldblatt hearts (delta 14%, n.s.). 24 weeks after operation, oxygen consumption related to wall stress averaged over the entire heart cycle amounted to 16.1 mumoles O2/g x min, in age-matched controls 20.5 mumoles O2/g x min (delta 21%, p less than 0.05). When wall stress was averaged over systole, oxygen consumption of the Goldblatt hearts amounted to 0.080 mumoles O2/g x beat, and in the controls 0.107 mumoles O2/g x beat (delta 25%, p less than 0.0005). The proportion of VM-3 increased from 33.5% in the controls to 43.2% in the hypertrophied hearts (delta 29%, p less than 0.05). The present findings indicate that the reduced oxygen consumption of the pressure-loaded heart should be attributed to a redistribution of myosin isoenzymes. The transformation of myocardium into a slower, but more efficiently working muscle due to an increase in VM-3 can be interpreted as an adaptational process.
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46
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Williams JF, Potter RD, Hern DL, Mathew B, Deiss WP. Hydroxyproline and passive stiffness of pressure-induced hypertrophied kitten myocardium. J Clin Invest 1982; 69:309-14. [PMID: 6460045 PMCID: PMC370980 DOI: 10.1172/jci110454] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Passive stiffness and hydroxyproline content of myocardium hypertrophied by pressure-loading were determined in kittens 2, 8-16, and 24-52 wk after pulmonary artery banding, which initially elevated right ventricular systolic pressure by 10-15 mm Hg. Right ventricular mass increased by approximately 75%, three-quarters of which occurred during the first 2 wk after banding. Passive stiffness was assessed from resting length-tension relations of isometrically contracting isolated right ventricular papillary muscles. Stiffness constants, alpha and beta were determined from the relationship sigma = alpha (e beta epsilon - 1) where sigma = stress and epsilon = Lagrangian strain. Elastic stiffness (d sigma/d epsilon) was derived from: d sigma/d epsilon = beta sigma + beta alpha. Right ventricular hydroxyproline increased in proportion to muscle mass so that hydroxyproline concentration remained unchanged after banding. Both alpha, beta, and elastic stiffness-stress relations were similar to values in nonbanded controls. Thus, we did not observe an increase in passive stiffness or hydroxyproline concentration of pressure-stiffness or hydroxyproline concentration of pressure-induced hypertrophied myocardium in contrast to most previous studies.
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Burns AH, Montini J. Myocardium in hypertrophy: oxygen consumption by isolated cardiac myocytes and working hearts from spontaneously hypertensive rats. Life Sci 1982; 30:29-37. [PMID: 7054634 DOI: 10.1016/0024-3205(82)90632-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Oxygen consumption was measured on suspensions of calcium tolerant myocytes obtained from hearts of Spontaneously Hypertensive Rats (SHR) and normotensive Wistar Kyoto Rats (WKY). Oxygen consumptions of the isolated cells were not significantly different from each other either in the presence or absence of added calcium (1.5 mM). Additionally, there was excellent agreement between the oxygen consumption of the isolated cells and estimates of basal oxygen consumption between work and myocardial oxygen utilization in isolated perfused working hearts. At any given workload there was no significant difference in oxygen consumption between SHR hearts and WKY hearts. The mechanical performance of the SHR hearts was lower compared to that of the WKY hearts at low preloads. At high preloads and high afterloads the SHR hearts developed higher pressures than did hearts obtained from WKY rats. The data suggest that: (1) basal oxygen consumption of the two hearts are similar and (b) the contractile defects in the SHR heart are not the result of hypoxia.
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Moravec J, Moravec M, Hatt PY. Rate of pyridine nucleotide oxidation and cytochrome oxidase interaction with intracellular oxygen in hearts from rats with compensated volume overload. Pflugers Arch 1981; 392:106-14. [PMID: 6275342 DOI: 10.1007/bf00581257] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Attarian DE, Jones RN, Currie WD, Hill RC, Sink JD, Olsen CO, Randolph Chitwood W, Wechsler AS. Characteristics of chronic left ventricular hypertrophy induced by subcoronary valvular aortic stenosis. J Thorac Cardiovasc Surg 1981. [DOI: 10.1016/s0022-5223(19)37603-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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50
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Lenzi S, Cuccurullo F. "Salient metabolic features in the myocardial cell". PHARMACOLOGICAL RESEARCH COMMUNICATIONS 1981; 13:251-63. [PMID: 6451875 DOI: 10.1016/s0031-6989(81)80106-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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