Sarcomere length nanometry in rat neonatal cardiomyocytes expressed with α-actinin-AcGFP in Z discs

Seine A. Shintani, Kotaro Oyama, Fuyu Kobirumaki-Shimozawa, Takashi Ohki, Shin'ichi Ishiwata, Norio Fukuda

    Research output: Contribution to journalArticle

    18 Citations (Scopus)

    Abstract

    Nanometry is widely used in biological sciences to analyze the movement of molecules or molecular assemblies in cells and in vivo. In cardiac muscle, a change in sarcomere length (SL) by a mere ̃100 nm causes a substantial change in contractility, indicating the need for the simultaneous measurement of SL and intracellular Ca2+ concentration ([Ca2+]i) in cardiomyocytes at high spatial and temporal resolution. To accurately analyze the motion of individual sarcomeres with nanometer precision during excitation-contraction coupling, we applied nanometry techniques to primary-cultured rat neonatal cardiomyocytes. First, we developed an experimental system for simultaneous nanoscale analysis of single sarcomere dynamics and [Ca2+]i changes via the expression of AcGFP in Z discs. We found that the averaging of the lengths of sarcomeres along the myocyte, a method generally used in today's myocardial research, caused marked underestimation of sarcomere lengthening speed because of the superpositioning of different timings for lengthening between sequentially connected sarcomeres. Then, we found that after treatment with ionomycin, neonatal myocytes exhibited spontaneous sarcomeric oscillations (cell-SPOCs) at partial activation with blockage of sarcoplasmic reticulum functions, and the waveform properties were indistinguishable from those obtained in electric field stimulation. The myosin activator omecamtiv mecarbil markedly enhanced Z-disc displacement during cell-SPOC. Finally, we interpreted the present experimental findings in the framework of our mathematical model of SPOCs. The present experimental system has a broad range of application possibilities for unveiling single sarcomere dynamics during excitation-contraction coupling in cardiomyocytes under various settings.

    Original languageEnglish
    Pages (from-to)513-524
    Number of pages12
    JournalJournal of General Physiology
    Volume143
    Issue number4
    DOIs
    Publication statusPublished - 2014

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    Actinin
    Sarcomeres
    Cardiac Myocytes
    Excitation Contraction Coupling
    Muscle Cells
    Ionomycin
    Biological Science Disciplines
    Sarcoplasmic Reticulum
    Myosins
    Electric Stimulation
    Myocardium
    Theoretical Models

    ASJC Scopus subject areas

    • Physiology
    • Medicine(all)

    Cite this

    Shintani, S. A., Oyama, K., Kobirumaki-Shimozawa, F., Ohki, T., Ishiwata, S., & Fukuda, N. (2014). Sarcomere length nanometry in rat neonatal cardiomyocytes expressed with α-actinin-AcGFP in Z discs. Journal of General Physiology, 143(4), 513-524. https://doi.org/10.1085/jgp.201311118

    Sarcomere length nanometry in rat neonatal cardiomyocytes expressed with α-actinin-AcGFP in Z discs. / Shintani, Seine A.; Oyama, Kotaro; Kobirumaki-Shimozawa, Fuyu; Ohki, Takashi; Ishiwata, Shin'ichi; Fukuda, Norio.

    In: Journal of General Physiology, Vol. 143, No. 4, 2014, p. 513-524.

    Research output: Contribution to journalArticle

    Shintani, SA, Oyama, K, Kobirumaki-Shimozawa, F, Ohki, T, Ishiwata, S & Fukuda, N 2014, 'Sarcomere length nanometry in rat neonatal cardiomyocytes expressed with α-actinin-AcGFP in Z discs', Journal of General Physiology, vol. 143, no. 4, pp. 513-524. https://doi.org/10.1085/jgp.201311118
    Shintani, Seine A. ; Oyama, Kotaro ; Kobirumaki-Shimozawa, Fuyu ; Ohki, Takashi ; Ishiwata, Shin'ichi ; Fukuda, Norio. / Sarcomere length nanometry in rat neonatal cardiomyocytes expressed with α-actinin-AcGFP in Z discs. In: Journal of General Physiology. 2014 ; Vol. 143, No. 4. pp. 513-524.
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