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KMID : 0606920070150040212
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Biomolecules & Therapeutics
2007 Volume.15 No. 4 p.212 ~ p.217
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Enhancement of Ca2+ Current Does Not Regulate the Speed of Depolarization-induced Ca2+ Propagation Wave in Rat Atrial Myocytes
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Woo Sun-Hee
Hwang Seon-Hwa
Kim Joon-Chul
Morad Martin
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Abstract
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In atrial myocytes, lacking t-tubules, Ca2+ current (ICa)-initiated Ca2+ release at the peripheral junctional
sites propagates into the interior of the cell by diffusion of Ca2+. We have previously reported that time of
activation of the central sites is independent of ICa. In the present study we have probed the effects of Bay K 8644
on Ca2+ propagation wave to the center of the myocyte using rapid 2-D confocal Ca2+ imaging in the rat atrial
myocytes. Enhancement of ICa by Bay K 8644 accelerated the rate of peripheral Ca2+ release, but did not affect the
speed of propagation of central release. In contrast, enhancement of ICa by intracellular cAMP reduced the magnitude
of peripheral and central Ca2+ transients, but significantly accelerated the speed of central Ca2+ release. Our
data suggest that the speed of central Ca2+ propagation triggered by ICa is not regulated by the magnitude of either
ICa or local cytosolic Ca2+ releases.
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KEYWORD
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Atrial Ca2+ signaling, Ca2+ propagation, Mitochondria, Ca2+ current
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