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Báo cáo khoa học: Synchronous Ca2+ oscillation emerges from voltage fluctuations of Ca2+ stores

Synchronous Ca 2+ oscillation occurs in various cell types to regulate cell-ular functions. However, the mechanism for synchronization of Ca 2+ increases between cells remains unclear. Recently, synchronous oscillatory changes in the membrane potential of internal Ca 2+ stores were recorded using an organelle-specific voltage-sensitive dye [Yamashita et al. (2006) FEBS J273, 3585–3597], and an electrical coupling model of the synchro-nization of store potentials and Ca 2+ releases has been proposed [Yamash-ita (2006) FEBS Lett580, 4979–4983] | ễFEBS Journal Synchronous Ca2 oscillation emerges from voltage fluctuations of Ca2 stores Masayuki Yamashita Department of Physiology I Nara MedicalUniversity Kashihara Japan Keywords Ca2 oscillation Ca2 release fluorescence voltage measurement neuronal development synchronization Correspondence M. Yamashita Department of Physiology I Nara MedicalUniversity Shijo-cho 840 Kashihara 634-8521 Japan Fax 81 744 29 0306 Tel 81 744 29 8827 E-mail yama@naramed-u.ac.jp Received 14 March 2008 revised 5 May 2008 accepted 10 June 2008 doi 10.1111 j.1742-4658.2008.06543.x Synchronous Ca2 oscillation occurs in various cell types to regulate cellular functions. However the mechanism for synchronization of Ca2 increases between cells remains unclear. Recently synchronous oscillatory changes in the membrane potential of internal Ca2 stores were recorded using an organelle-specific voltage-sensitive dye Yamashita et al. 2006 FEBS J 273 3585-3597 and an electrical coupling model of the synchronization of store potentials and Ca2 releases has been proposed Yamash-ita 2006 FEBS Lett 580 4979-4983 . This model is based on capacitative coupling by which transient voltage changes can be synchronized but oscillatory slow potentials cannot be communicated. Another candidate mechanism is synchronization of action potentials and ensuing Ca2 influx through voltage-dependent Ca channels. The present study addresses the question of whether Ca2 increases are synchronized by action potentials and how oscillatory store potentials are synchronized across the cells. Electrophysiological and Ca2 -sensitive fluorescence measurements in early embryonic chick retina showed that synchronous Ca2 oscillation was caused by releases of Ca2 from Ca2 stores without any evidence of action potentials in retinal neuroepithelial cells or newborn neurons. Highspeed fluorescence measurement of store membrane potential surprisingly revealed that the synchronous oscillatory changes in the store potential were periodic