The beginning of the calcium transient in rat embryonic heart.
Although many researchers have tried to observe the beginning of the heartbeat, no study has shown the beginning of the calcium transient. Here, we evaluate the beginning of the calcium transient in the Wistar rat heart. We first tried to reveal when the heart of the Wistar rat begins to contract because no previous study has evaluated the beginning of the heartbeat in Wistar rats. Observation of embryos transferred to a small incubator mounted on a microscope revealed that the heart primordium, the so-called cardiac crescent, began to contract at embryonic day 9.99-10.13. Observation of embryos loaded with fluo-3 AM revealed that the beginning of the calcium transient precedes the initiation of contraction which precedes the appearance of the linear heart tube. Nifedipine (1 μM), but not ryanodine (1 μM), abolished the calcium transients. These results indicate that calcium transients in the early embryonic period involve exclusively calcium entry through L-type calcium channels in contrast to the situation in mature hearts. This study provides the first demonstration of the relationship between morphological changes in the heart primordium and the beginning of the calcium transient and contraction.
Department of Cellular Physiology and Signal Transduction, Sapporo Medical University School of Medicine, South 1 West 17, Chuo-ku, Sapporo, 060-8556, Japan. tkobaya@sapmed.ac.jp
Takeshi
T
Kobayashi
Sachiko
S
Maeda
Nobutoshi
N
Ichise
Tatsuya
T
Sato
Takehito
T
Iwase
Sumihiko
S
Seki
Yoichi
Y
Yamada
Noritsugu
N
Tohse
D000814:Aniline Compounds / Q000737:chemistry; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D004622:Embryo, Mammalian; D005260:Female; D006321:Heart / Q000196:embryology*; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D014966:Xanthenes / Q000737:chemistry
D000814:Aniline Compounds; D020746:Calcium Channels, L-Type; D014966:Xanthenes; D012433:Ryanodine; C059715:Fluo-3; D009543:Nifedipine; D002118:Calcium
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