動物細胞における膜電位・細胞内Ca2+振動

概要

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A variety of nammalian cells exhibit membrane potential oscillations composed of repeated hyperpolarizations. Such hyperpolarizing oscillations are usually caused by cyclic increases in the cytosolic Ca2+ ions, which in turn, periodically stimulate Ca2+-activated K+ channels. Intracellular Ca2+ oscillations could be brought about by a feedback relationship between an autocatalytic Ca2+ input and a delayed Ca2+ output. In mouse fibroblastic L cells, the operation of Ca2+ channels and that of Ca2+ pump are involved in the oscillations. The Ca2+ channels are activated by stimulation of membrane receptors to complement components (such as Clq) and nucleotides (such as ATP), which are chemotactic factors for the firboblasts. In human epithelial Intestine 407 cells, stimulation of receptors to intestinal secretagogues (such as acetylcholine, histamine, serotonin and VlP) gives rise to Ca2+ release from some intracellular calcium stores. Under appropriate conditions, receptor stimulation by agonists was found to lead to generation of the oscillations in both cell species. Thus, it is strongly suggested that oscillations of membrane potential and cytosolic Ca2+ occur in the recepor-activated fibroblasts and enterocytes in vivo, and that the oscillations play an important role in Ca2+-mediated cell activities such as fibroblast chemotaxis and intestinal secretion.
日本膜学会の論文