Although many researchers have examined the embryonic heart, the precise relationship between the morphological changes of the heart and heart function, i.e., excitation- contraction coupling, around the period of the beginning of the heartbeat remains obscure. Here, we recorded and evaluated the beginning of the calcium transient and contraction of the Wistar rat heart. The heart primordium, the so-called cardiac crescent, of Wistar rats begins to contract at embryonic day 9.99-10.13. The contracting area is initially small and becomes enlarged with time. Repetitive calcium transients are observed regularly in the whole heart primordium, before the initiation of contraction. Nifedipine, but not ryanodine, abolished the calcium transients. Thapsigargin did not affect the calcium transients. These results indicate that the calcium transients involve exclusively calcium entry through L-type calcium channels, in contrast to the situation in mature hearts. This study reveals the precise relationship between morphological changes in the heart primordium and the beginning of the calcium transient and contraction.
37th Congress of IUPS (Birmingham, UK) (2013) Proc 37th IUPS, PCD021
Poster Communications: The beginning of the calcium transient and contraction in rat embryonic heart.
T. Kobayashi1, S. Maeda1, N. Ichise1, T. Sato1, T. Miyakawa1, Y. Yamada1, N. Tohse1
1. Cellular Physiology and Signal Transduction, Sapporo Medical University School of Medicine, Sapporo, Japan.
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Where applicable, experiments conform with Society ethical requirements.