抄録
Oscillation in the concentration of cytosolic Ca2+ (calcium oscillation) is known to be caused by repetitive release of calcium from intracellular calcium stores. For further understanding the mechanism of calcium oscillation, we simultaneously measure cytosolic calcium concentration ([Ca2+]c) and intraluminal calcium concentration of intracellular calcium store ([Ca2+]s), and studied differences of time course between [Ca2+]c and [Ca2+]s in bullfrog sympathetic ganglion cells. Cells were loaded with two fluorescent calcium indicators, Oregon Green 488 BAPTA-5N for measuring [Ca2+]c and Furaptra for [Ca2+]s, respectively. Calcium oscillation was induced by the application of caffeine. [Ca2+]s decreased rapidly and then increased gradually. After [Ca2+]s reached to the threshold level for calcium release which was below the resting level, calcium was released again from calcium stores. Calcium concentration changes in [Ca2+]c and [Ca2+]s were not just the mirror image and the decaying phase of [Ca2+]c was faster than that of [Ca2+]s, suggesting that decaying phase of [Ca2+]c may be accelerated by efflux of calcium to extracellular space and/or uptake to other cytosolic organ. [Jpn J Physiol 54 Suppl:S159 (2004)]
