@misc{oai:repo.qst.go.jp:00079074,
 author = {Ishii, Shuya and Oyama, Kotaro and Fuyu, Kobirumaki-Shimozawa and Shin'ichi, Ishiwata and Fukuda, Norio and Ishii, Shuya and Oyama, Kotaro},
 month = {Mar},
 note = {During excitation-contraction coupling of the muscle, sarcomeres are activated via thin filament structural changes, i.e., from the “off” state to the “on” state, in response to a rise in the intracellular Ca2+concentration. We systematically investigated the effects of rapid heating by infra-red (IR) laser irradiation on the sliding of thin filaments reconstituted with human α-tropomyosin (Tm), bovine ventricular troponin (Tn), or rabbit fast skeletal Tm-Tn complex in the in vitro motility assay. Temperature was varied from room temperature (R.T.; ~24˚C) to ~45˚C within 2-10 s. With increasing temperature, the sliding velocity of F-actin and thin filaments reconstituted with cardiac Tm-Tn was accelerated in the presence of ATP and Ca2+, with a temperature coefficient (Q10) of ~2 (R.T. ~41˚C). In the absence of Ca2+ and in the presence of ATP at R.T., thin filaments reconstituted with cardiac regulatory proteins did not move; however, IR laser irradiation elicited movements of reconstituted thin filaments with a Q10 of 5.5. Likewise, IR laser irradiation elicited movements of thin filaments reconstituted with fast skeletal Tm-Tn with a Q10 of 11.0, showing higher sensitivity to temperature. The heating-induced acceleration was observed in the presence of Ca2+ for cardiac and fast skeletal thin filaments, with temperature dependency >2-fold less in both cases. These findings suggest that, 1) the “on-off” equilibrium of the cardiac thin filament state is partially shifted toward the “on” state in diastole at the body temperature, enabling rapid and efficient myocardial dynamics in systole, and 2) the higher temperature dependency for fast skeletal thin filaments is optimized for the muscle’s physiological properties in vivo., 第97回日本生理学会大会},
 title = {Microscopic heat pulses induce activation of thin filaments in striated muscle},
 year = {2020}
}