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  • American Physiological Society  (6)
  • Goto, Kazuko  (6)
  • 1
    Online Resource
    Online Resource
    Autophagy limits acute myocardial infarction induced by permanent coronary artery occlusion
    American Physiological Society ; 2011
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 300, No. 6 ( 2011-06), p. H2261-H2271
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 300, No. 6 ( 2011-06), p. H2261-H2271
    Abstract: Ischemia is known to potently stimulate autophagy in the heart, which may contribute to cardiomyocyte survival. In vitro, transfection with small interfering RNAs targeting Atg5 or Lamp-2 (an autophagy-related gene necessary, respectively, for the initiation and digestion step of autophagy), which specifically inhibited autophagy, diminished survival among cultured cardiomyocytes subjected to anoxia and significantly reduced their ATP content, confirming an autophagy-mediated protective effect against anoxia. We next examined the dynamics of cardiomyocyte autophagy and the effects of manipulating autophagy during acute myocardial infarction in vivo. Myocardial infarction was induced by permanent ligation of the left coronary artery in green fluorescent protein-microtubule-associated protein 1 light chain 3 (GFP-LC3) transgenic mice in which GFP-LC3 aggregates to be visible in the cytoplasm when autophagy is activated. Autophagy was rapidly (within 30 min after coronary ligation) activated in cardiomyocytes, and autophagic activity was particularly strong in salvaged cardiomyocytes bordering the infarcted area. Treatment with bafilomycin A1, an autophagy inhibitor, significantly increased infarct size (31% expansion) 24 h postinfarction. Interestingly, acute infarct size was significantly reduced (23% reduction) in starved mice showing prominent autophagy before infarction. Treatment with bafilomycin A1 reduced postinfarction myocardial ATP content, whereas starvation increased myocardial levels of amino acids and ATP, and the combined effects of bafilomycin A1 and starvation on acute infarct size offset one another. The present findings suggest that autophagy is an innate and potent process that protects cardiomyocytes from ischemic death during acute myocardial infarction.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.01056.2010
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2011
    detail.hit.zdb_id: 1477308-9
    SSG: 12
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  • 2
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    Postinfarction gene therapy with adenoviral vector expressing decorin mitigates cardiac remodeling and dysfunction
    American Physiological Society ; 2009
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 297, No. 4 ( 2009-10), p. H1504-H1513
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 297, No. 4 ( 2009-10), p. H1504-H1513
    Abstract: The small leucine-rich proteoglycan decorin is a natural inhibitor of transforming growth factor-β (TGF-β) and exerts antifibrotic effects in heart and to stimulate skeletal muscle regeneration. We investigated decorin's chronic effects on postinfarction cardiac remodeling and dysfunction. Myocardial infarction (MI) was induced in mice by left coronary artery ligation. An adenoviral vector encoding human decorin (Ad. CAG-decorin) was then injected into the hindlimbs on day 3 post-MI (control, Ad.CAG-LacZ). Four weeks post-MI, the decorin-treated mice showed significant mitigation of the left ventricular dilatation and dysfunction seen in control mice. Although infarct size did not differ between the two groups, the infarcted wall thickness was greater and the segmental length of the infarct was smaller in decorin-treated mice. In addition, cellular components, including myofibroblasts and blood vessels, were more abundant within the infarcted area in decorin-treated mice, and fibrosis was significantly reduced in both the infarcted and noninfarcted areas of the left ventricular wall. Ten days post-MI, there was greater cell proliferation and less apoptosis among granulation tissue cells in the infarcted areas of decorin-treated mice. The treatment, however, did not affect proliferation and apoptosis of salvaged cardiomyocytes. Although decorin gene therapy did not affect TGF-β1 expression in the infarcted heart, it inhibited Smad2/3 activation (downstream mediators of TGF-β signaling). In summary, postinfarction decorin gene therapy mitigated cardiac remodeling and dysfunction by altering infarct tissue noncardiomyocyte dynamics and preventing cardiac fibrosis, accompanying inhibition of Smad2/3 activation.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.00194.2009
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2009
    detail.hit.zdb_id: 1477308-9
    SSG: 12
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  • 3
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    Online Resource
    Morphological and biochemical characterization of basal and starvation-induced autophagy in isolated adult rat cardiomyocytes
    American Physiological Society ; 2008
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 295, No. 4 ( 2008-10), p. H1599-H1607
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 295, No. 4 ( 2008-10), p. H1599-H1607
    Abstract: Autophagy is simultaneously a mode of programmed cell death and an important physiological process for cell survival, but its pathophysiological significance in cardiac myocytes remains largely unknown. We induced autophagy in isolated adult rat ventricular cardiomyocytes (ARVCs) by incubating them in glucose-free, mannitol-supplemented medium for up to 4 days. Ultrastructurally, intracellular vacuoles containing degenerated subcellular organelles (e.g., mitochondria) were markedly apparent in the glucose-starved cells. Microtubule-associated protein-1 light chain 3 was significantly upregulated among the glucose-starved ARVCs than among the controls. After 4 days, glucose-starved ARVCs showed a significantly worse survival rate (19 ± 5.2%) than the controls (55 ± 8.3%, P 〈 0.005). Most dead ARVCs in both groups showed features of necrosis, and the rate of apoptosis did not differ between the groups. Two inhibitors of autophagy, 3-methyladenine (3-MA) and leupeptin, significantly and dose-dependently reduced the viability of both control and glucose-starved ARVCs and caused specific morphological alterations; 3-MA reduced autophagic findings, whereas leupeptin greatly increased the numbers and the sizes of vacuoles that contained incompletely digested organelles. The knockdown of the autophagy-related genes with small interfering RNA also reduced the glucose-starved ARVCs viability, but rapamycin, an autophagy enhancer, improved it. Reductions in the ATP content of ARVCs caused by glucose depletion were exacerbated by the inhibitors while attenuated by rapamycin, suggesting that autophagy inhibition might accelerate energy depletion, leading to necrosis. Taken together, our findings suggest that autophagy in cardiomyocytes reflects a prosurvival, compensatory response to stress and that autophagic cardiomyocyte death represents an unsuccessful outcome due to necrosis.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.91449.2007
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2008
    detail.hit.zdb_id: 1477308-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 4
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    Online Resource
    OPC-28326, a selective peripheral vasodilator with angiogenic activity, mitigates postinfarction cardiac remodeling
    American Physiological Society ; 2015
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 309, No. 1 ( 2015-07-01), p. H213-H221
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 309, No. 1 ( 2015-07-01), p. H213-H221
    Abstract: Although OPC-28326, 4-( N-methyl-2-phenylethylamino)-1-(3,5-dimethyl-4-propionyl-aminobenzoyl) piperidine hydrochloride monohydrate, was developed as a selective peripheral vasodilator with α 2 -adrenergic antagonist properties, it also reportedly exhibits angiogenic activity in an ischemic leg model. The purpose of this study was to examine the effect of OPC-28326 on the architectural dynamics and function of the infarcted left ventricle during the chronic stage of myocardial infarction. Myocardial infarction was induced in male C3H/He mice, after which the mice were randomly assigned into two groups: a control group receiving a normal diet and an OPC group whose diet contained 0.05% OPC-28326. The survival rate among the mice ( n = 18 in each group) 4 wk postinfarction was significantly greater in the OPC than control group (83 vs. 44%; P 〈 0.05), and left ventricular remodeling and dysfunction were significantly mitigated. Histologically, infarct wall thickness was significantly greater in the OPC group, due in part to an abundance of nonmyocyte components, including blood vessels and myofibroblasts. Five days postinfarction, Ki-67-positive proliferating cells were more abundant in the granulation tissue in the OPC group, and there were fewer apoptotic cells. These effects were accompanied by activation of myocardial Akt and endothelial nitric oxide synthase. Hypoxia within the infarct issue, assessed using pimonidazole staining, was markedly attenuated in the OPC group. In summary, OPC-28326 increased the nonmyocyte population in infarct tissue by increasing proliferation and reducing apoptosis, thereby altering the tissue dynamics such that wall stress was reduced, which might have contributed to a mitigation of postinfarction cardiac remodeling and dysfunction.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.00062.2015
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2015
    detail.hit.zdb_id: 1477308-9
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Repeated phlebotomy augments angiogenesis to improve blood flow in murine ischemic legs
    American Physiological Society ; 2010
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 299, No. 2 ( 2010-08), p. H372-H378
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 299, No. 2 ( 2010-08), p. H372-H378
    Abstract: Anemia may accelerate angiogenesis in ischemic organs through its ability to augment tissue hypoxia-induced generation of several known angiogenic factors and to increase erythropoietin levels, which are also potently angiogenic. We examined the effect of controlled phlebotomy (bloodletting) on blood flow in a mouse ischemic leg model. We ligated the right femoral artery of BALB/c mice. In the phlebotomy group, 200 μl of blood were drawn from the tail vein once a week. After 4 wk, blood flow in the ischemic leg was significantly better in the phlebotomy group (flow ratio of the ischemic to nonischemic leg, 0.87 ± 0.04) than the control group (0.59 ± 0.05, P 〈 0.05), and capillary density was significantly higher. Repeated phlebotomy increased serum erythropoietin levels as well as the expression of hypoxia-inducible transcription factor-1α and vascular endothelial growth factor and both the expression and activity of Akt and endothelial nitric oxide synthase (eNOS) in ischemic legs. Treatment with wortmannin or N ω -nitro-l-arginine methyl ester significantly attenuated the phlebotomy-induced improvement of blood flow. In addition, fluorescence-activated cell sorting analysis revealed an increase in circulating peripheral endothelial progenitor cells in the phlebotomy group, and treatment with AMD3100, a specific inhibitor of the chemokine receptor CXCR4, blocked the beneficial effect of phlebotomy. These findings suggest that repeated phlebotomy improves blood flow in ischemic legs through an angiogenic action that involves the Akt/eNOS pathway, endothelial progenitor cell mobilization, and their complicated cross talk. An adequately controlled phlebotomy might be one method by which to induce therapeutic angiogenesis.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.00035.2010
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2010
    detail.hit.zdb_id: 1477308-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 6
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    Online Resource
    Treatment with an adenoviral vector encoding hepatocyte growth factor mitigates established cardiac dysfunction in doxorubicin-induced cardiomyopathy
    American Physiological Society ; 2008
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 294, No. 2 ( 2008-02), p. H1048-H1057
    Details
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 294, No. 2 ( 2008-02), p. H1048-H1057
    Abstract: Hepatocyte growth factor (HGF) reportedly exerts beneficial effects on the heart following myocardial infarction and during nonischemic cardiomyopathy, but the precise mechanisms underlying the latter have not been well elucidated. We generated nonischemic cardiomyopathy in mice by injecting them with doxorubicin (15 mg/kg ip). Two weeks later, when cardiac dysfunction was apparent, an adenoviral vector encoding human HGF gene (Ad.CAG-HGF, 1×10 11 particles/mouse) was injected into the hindlimb muscles; LacZ gene served as the control. Left ventricular dilatation and dysfunction normally seen 4 wk after doxorubicin administration were significantly mitigated in HGF-treated mice, as were the associated cardiomyocyte atrophy/degeneration and myocardial fibrosis. Myocardial expression of GATA-4 and a sarcomeric protein, myosin heavy chain, was downregulated by doxorubicin, but the expression of both was restored by HGF treatment. The protective effect of HGF against doxorubicin-induced cardiomyocyte atrophy was confirmed in an in vitro experiment, which also showed that neither cardiomyocyte apoptosis nor proliferation plays significant roles in the present model. Upregulation of c-Met/HGF receptor was noted in HGF-treated hearts. Among the mediators downstream of c-Met, the activation of extracellular signal-regulated kinase (ERK) was reduced by doxorubicin, but the activity was restored by HGF. Levels of transforming growth factor-β1 and cyclooxygenase-2 did not differ between the groups. Our findings suggest the HGF gene delivery exerts therapeutic antiatrophic/degenerative and antifibrotic effects on myocardium in cases of established cardiac dysfunction caused by doxorubicin. These beneficial effects appear to be related to HGF-induced ERK activation and upregulation of c-Met, GATA-4, and sarcomeric proteins.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    URL: Article
    DOI: 10.1152/ajpheart.01102.2007
    RVK:
    WA 15000
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2008
    detail.hit.zdb_id: 1477308-9
    SSG: 12
    Location Call Number Limitation Availability
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