Microscopic heat pulses induce contraction of cardiomyocytes without calcium transients

• Published in: Biochemical and biophysical research communications 2012-01, Vol.417 (1), p.607-612
• Main Authors: Oyama, Kotaro, Mizuno, Akari, Shintani, Seine A., Itoh, Hideki, Serizawa, Takahiro, Fukuda, Norio, Suzuki, Madoka, Ishiwata, Shin’ichi
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; AMBIENT TEMPERATURE; ANIMAL TISSUES; Animals; CALCIUM; Calcium - physiology; CALCIUM IONS; Calcium transients; Cardiac muscle; Cardiomyocytes; Cells, Cultured; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONTRACTION; Electrical stimuli; HEART; HEAT; Heat pulses; Hot Temperature; IR laser; LASER RADIATION; LASERS; Microscopes; Muscle Contraction; Muscle, Skeletal - physiology; Myocardial Contraction; Myocytes, Cardiac - physiology; OPTICAL MICROSCOPES; RATS; Skeletal muscle; Skin; Temperature changes; Temperature effects; Temperature requirements; TRANSIENTS; VISIBLE RADIATION
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2011.12.015

[Display omitted] ► Infra-red laser beam generates microscopic heat pulses. ► Heat pulses induce contraction of cardiomyocytes. ► Ca2+ transients during the contraction were not detected. ► Skinned cardiomyocytes in free Ca2+ solution also contracted. ► Heat pulses regulated the contractions without Ca2+ dynamics. It was recently demonstrated that laser irradiation can control the beating of cardiomyocytes and hearts, however, the precise mechanism remains to be clarified. Among the effects induced by laser irradiation on biological tissues, temperature change is one possible effect which can alter physiological functions. Therefore, we investigated the mechanism by which heat pulses, produced by infra-red laser light under an optical microscope, induce contractions of cardiomyocytes. Here we show that microscopic heat pulses induce contraction of rat adult cardiomyocytes. The temperature increase, ΔT, required for inducing contraction of cardiomyocytes was dependent upon the ambient temperature; that is, ΔT at physiological temperature was lower than that at room temperature. Ca2+ transients, which are usually coupled to contraction, were not detected. We confirmed that the contractions of skinned cardiomyocytes were induced by the heat pulses even in free Ca2+ solution. This heat pulse-induced Ca2+-decoupled contraction technique has the potential to stimulate heart and skeletal muscles in a manner different from the conventional electrical stimulations.