caa a22 4500 60624283X CHVBK 20210128101320.0 cr unu---uuuuu 210128e20150301xx s 000 0 eng 10.1007/s12551-015-0165-7 doi (NATIONALLICENCE)springer-10.1007/s12551-015-0165-7 Spontaneous oscillatory contraction (SPOC) in cardiomyocytes [Elektronische Daten] [Tatsuya Kagemoto, Amy Li, Cris dos Remedios, Shin'ichi Ishiwata] SPOC (spontaneous oscillatory contraction) is a characteristic state of the contractile system of striated (skeletal and cardiac) muscle that exists between the states of relaxation and contraction. For example, Ca-SPOCs occur at physiological Ca2+ levels (pCa ∼6.0), whereas ADP-SPOC occurs in the virtual absence of Ca2+ (pCa ≥ 8; relaxing conditions in the presence of MgATP), butin the presence of inorganic phosphate (Pi) and a high concentration of MgADP. The concentration of Mg-ADP necessary for SPOC is nearly equal to or greater than the MgATP concentration for cardiac muscle and is several times higher for skeletal muscle. Thus, the cellular conditions for SPOC are broader in cardiac muscle than in skeletal muscle. During these SPOCs, each sarcomere in a myofibril undergoes length oscillation that has a saw-tooth waveform consisting of a rapid lengthening and a slow shortening phase. The lengthening phase of one half of a sarcomere is transmitted to the adjacent half of the sarcomere successively, forming a propagating wave (termed a SPOC wave). The SPOC waves are synchronized across the cardiomyocytes resulting in a visible wave of successive contractions and relaxations termed the SPOC wave. Experimentally, the SPOC period (and therefore the velocity of SPOC wave) is observed in demembranated cardiomyocytes and can be prepared from a wide range of animal hearts. These periods correlate well with the resting heartbeats of a wide range of mammals (rat, rabbit, dog, pig and cow). Preliminary experiments showed that the SPOC properties of human cardiomyocytes are similar to the heartbeat of a large dog or a pig. This correlation suggests that SPOCs may play a fundamental role in the heart. Here, we briefly summarize a range of SPOC parameters obtained experimentally, and relate them to a theoretical model to explain those characteristics. Finally, we discuss the possible significance of these SPOC properties in each and everyheartbeat. International Union for Pure and Applied Biophysics (IUPAB) and Springer-Verlag Berlin Heidelberg, 2015 SPOC nationallicence Spontaneous oscillatory contraction nationallicence SPOC wave nationallicence Heartbeat nationallicence Cardiomyocytes nationallicence Sarcomere nationallicence Kagemoto Tatsuya Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, 169-8555, Shinjuku-ku, Tokyo, Japan aut Li Amy Muscle Research Unit, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, 2006, Sydney, Australia aut dos Remedios Cris Muscle Research Unit, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, 2006, Sydney, Australia aut Ishiwata Shin'ichi Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, 169-8555, Shinjuku-ku, Tokyo, Japan aut Biophysical Reviews Springer Berlin Heidelberg 7/1(2015-03-01), 15-24 1867-2450 7:1<15 2015 7 12551 https://doi.org/10.1007/s12551-015-0165-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s12551-015-0165-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kagemoto Tatsuya Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, 169-8555, Shinjuku-ku, Tokyo, Japan aut NATIONALLICENCE 700 1- Li Amy Muscle Research Unit, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, 2006, Sydney, Australia aut NATIONALLICENCE 700 1- dos Remedios Cris Muscle Research Unit, Discipline of Anatomy & Histology, Bosch Institute, University of Sydney, 2006, Sydney, Australia aut NATIONALLICENCE 700 1- Ishiwata Shin'ichi Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, 169-8555, Shinjuku-ku, Tokyo, Japan aut NATIONALLICENCE 773 0- Biophysical Reviews Springer Berlin Heidelberg 7/1(2015-03-01), 15-24 1867-2450 7:1<15 2015 7 12551