Novel insights on the relationship between T-tubular defects and contractile dysfunction in a mouse model of hypertrophic cardiomyopathy

C. Crocini, C. Ferrantini, M. Scardigli, R. Coppini, L. Mazzoni, E. Lazzeri, J. M. Pioner, B. Scellini, A. Guo, L. S. Song, P. Yan, L. M. Loew, Jil C Tardiff, C. Tesi, F. Vanzi, E. Cerbai, F. S. Pavone, L. Sacconi, C. Poggesi

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Abnormalities of cardiomyocyte Ca2+ homeostasis and excitation-contraction (E-C) coupling are early events in the pathogenesis of hypertrophic cardiomyopathy (HCM) and concomitant determinants of the diastolic dysfunction and arrhythmias typical of the disease. T-tubule remodelling has been reported to occur in HCM but little is known about its role in the E-C coupling alterations of HCM. Here, the role of T-tubule remodelling in the electro-mechanical dysfunction associated to HCM is investigated in the Δ160E cTnT mouse model that expresses a clinically-relevant HCM mutation. Contractile function of intact ventricular trabeculae is assessed in Δ160E mice and wild-type siblings. As compared with wild-type, Δ160E trabeculae show prolonged kinetics of force development and relaxation, blunted force-frequency response with reduced active tension at high stimulation frequency, and increased occurrence of spontaneous contractions. Consistently, prolonged Ca2+ transient in terms of rise and duration are also observed in Δ160E trabeculae and isolated cardiomyocytes. Confocal imaging in cells isolated from Δ160E mice reveals significant, though modest, remodelling of T-tubular architecture. A two-photon random access microscope is employed to dissect the spatio-temporal relationship between T-tubular electrical activity and local Ca2+ release in isolated cardiomyocytes. In Δ160E cardiomyocytes, a significant number of T-tubules (>20%) fails to propagate action potentials, with consequent delay of local Ca2+ release. At variance with wild-type, we also observe significantly increased variability of local Ca2+ transient rise as well as higher Ca2+-spark frequency. Although T-tubule structural remodelling in Δ160E myocytes is modest, T-tubule functional defects determine non-homogeneous Ca2+ release and delayed myofilament activation that significantly contribute to mechanical dysfunction.

Original languageEnglish (US)
Pages (from-to)42-51
Number of pages10
JournalJournal of Molecular and Cellular Cardiology
Volume91
DOIs
StatePublished - Feb 1 2016

Keywords

  • Excitation-contraction coupling
  • Hypertrophic cardiomyopathy
  • Imaging
  • Non-linear microscopy
  • T-tubules

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Fingerprint Dive into the research topics of 'Novel insights on the relationship between T-tubular defects and contractile dysfunction in a mouse model of hypertrophic cardiomyopathy'. Together they form a unique fingerprint.

  • Cite this

    Crocini, C., Ferrantini, C., Scardigli, M., Coppini, R., Mazzoni, L., Lazzeri, E., Pioner, J. M., Scellini, B., Guo, A., Song, L. S., Yan, P., Loew, L. M., Tardiff, J. C., Tesi, C., Vanzi, F., Cerbai, E., Pavone, F. S., Sacconi, L., & Poggesi, C. (2016). Novel insights on the relationship between T-tubular defects and contractile dysfunction in a mouse model of hypertrophic cardiomyopathy. Journal of Molecular and Cellular Cardiology, 91, 42-51. https://doi.org/10.1016/j.yjmcc.2015.12.013