Impaired left ventricular mechanical and energetic function in mice after cardiomyocyte-specific excision of Serca2.

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  • Additional Information
    • Source:
      Publisher: American Physiological Society Country of Publication: United States NLM ID: 100901228 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1522-1539 (Electronic) Linking ISSN: 03636135 NLM ISO Abbreviation: Am J Physiol Heart Circ Physiol Subsets: MEDLINE
    • Publication Information:
      Original Publication: Bethesda, Md. : American Physiological Society,
    • Subject Terms:
      Energy Metabolism* ; Ventricular Function, Left*; Myocytes, Cardiac/*enzymology ; Sarcoplasmic Reticulum Calcium-Transporting ATPases/*deficiency ; Ventricular Dysfunction, Left/*enzymology; Animals ; Excitation Contraction Coupling ; Fatty Acids/metabolism ; Genotype ; Glucose/metabolism ; Mice ; Mice, Knockout ; Models, Cardiovascular ; Myocardial Contraction ; Oxygen Consumption ; Phenotype ; Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics ; Time Factors ; Ventricular Dysfunction, Left/genetics ; Ventricular Dysfunction, Left/physiopathology
    • Abstract:
      Sarco(endo)plasmic reticulum Ca2+ -ATPase (SERCA)2 transports Ca2+ from the cytosol into the sarcoplasmic reticulum of cardiomyocytes and is essential for maintaining myocardial Ca2+ handling and thus the mechanical function of the heart. SERCA2 is a major ATP consumer in excitation-contraction coupling but is regarded to contribute to energetically efficient Ca2+ handling in the cardiomyocyte. Previous studies using cardiomyocyte-specific SERCA2 knockout (KO) mice have demonstrated that decreased SERCA2 activity reduces the Ca2+ transient amplitude and induces compensatory Ca2+ transport mechanisms that may lead to more inefficient Ca2+ transport. In this study, we examined the relationship between left ventricular (LV) function and myocardial O2 consumption (MVo2) in ex vivo hearts from SERCA2 KO mice to directly measure how SERCA2 elimination influences mechanical and energetic features of the heart. Ex vivo hearts from SERCA2 KO hearts developed mechanical dysfunction at 4 wk and demonstrated virtually no working capacity at 7 wk. In accordance with the reported reduction in Ca2+ transient amplitude in cardiomyocytes from SERCA2 KO mice, work-independent MVo2 was decreased due to a reduced energy cost of excitation-contraction coupling. As these hearts also showed a marked impairment in the efficiency of chemomechanical energy transduction (contractile efficiency, i.e, work-dependent MVo2), hearts from SERCA2 KO mice were found to be mechanically inefficient. This ex vivo evaluation of mechanical and energetic function in hearts from SERCA2 KO mice brings together findings from previous experimental and mathematical modeling-based studies and demonstrates that reduced SERCA2 activity not only leads to mechanical dysfunction but also to energetic dysfunction.
    • Contributed Indexing:
      Keywords: contractile efficiency; mechanical efficiency; mechanoenergetics; myocardial oxygen consumption; pressure-volume area
    • Accession Number:
      0 (Fatty Acids)
      EC 3.6.3.8 (Sarcoplasmic Reticulum Calcium-Transporting ATPases)
      EC 7.2.2.10 (Atp2a2 protein, mouse)
      IY9XDZ35W2 (Glucose)
    • Publication Date:
      Date Created: 20140204 Date Completed: 20140526 Latest Revision: 20200930
    • Publication Date:
      20240628
    • Accession Number:
      10.1152/ajpheart.00741.2013
    • Accession Number:
      24486508