The excitation-contraction (E-C) coupling system during the development of heart can be investigated because of marked progression in electrophysiology and microfluorescence studies. During the developmental period, Ca2+ influx mediating the E-C coupling is mainly through the L-type Ca2+ channels. In the fetal period, T-type Ca2+ channels and the reverse mode of the Na-Ca exchange system also contribute to Ca2+ influx. These contributions probably reduce gradually until adulthood. The contraction of fetal cardiomyocytes has been thought to depend mainly on the Ca 2+ influx. However, recent studies reveal that immature sarcoplasmic reticulum (SR) already works in the early fetal period. Ca2+ spark, a local and unitary movement of Ca2+, can be observed in adult cardiomyocytes by the use of a confocal microscope. On the other hand, no Ca2+ spark is observed in fetal cardiomyocytes. The frequency of Ca2+-spark evocation increases during the postnatal period. Therefore a close distance between the L-type Ca2+ channel and the SR Ca2+-release channel is essential to the establishment of the Ca2+ spark.
CITATION STYLE
Tohse, N., Seki, S., Kobayashi, T., Tsutsuura, M., Nagashima, M., & Yamada, Y. (2004, February). Development of Excitation-Contraction Coupling in Cardiomyocytes. Japanese Journal of Physiology. https://doi.org/10.2170/jjphysiol.54.1
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