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 journalArticlepeer-review

    20 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

    ASJC Scopus subject areas

    • Physiology
    • Medicine(all)

    Fingerprint Dive into the research topics of 'Sarcomere length nanometry in rat neonatal cardiomyocytes expressed with α-actinin-AcGFP in Z discs'. Together they form a unique fingerprint.

    Cite this