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]
