[P3-2-13] Depolarization induced Ca2+ mobilization in rat odontoblasts
Keywords:象牙芽細胞、Ca2+、脱分極
Stimulation applied to the dentin surface induces activation of mechanosensitive ion channels and intracellular Ca2+ signaling in odontoblasts, resulting in the release of ATP from pannexin-1 to the extracellular space. The released ATP acts as an intercellular transmitter from odontoblast to odontoblast, as well as from odontoblasts to trigeminal ganglion neurons. The intercellular communication participates in dentin formation and generation of hypersensitivity. Although the cation influx via an activation of mechanosensitive ion channels induces plasma membrane depolarization, intracellular Ca2+ signaling by depolarization, and its participation to their cellular functions in odontoblasts remain unclear. It has been reported that odontoblasts express L- and T-type voltage-gated calcium channels. In this study, we investigated intracellular Ca2+ signaling pathway induced by plasma membrane depolarization in acutely isolated rat odontoblasts. Dental pulp slices were obtained from the incisors of newborn (7-9 days) Wistar rats. After enzymatic treatment, the primary cultured odontoblasts in the dental pulp slices were used for experiments within 24 hr culture period. Intracellular free calcium concentration ([Ca2+]i) was measured after loading of fura-2AM for 60 min. In the presence of extracellular Ca2+, high K+ (50 mM) solution, that induced depolarization, induced increases in [Ca2+]i in odontoblasts. In the absence of extracellular Ca2+, high K+ solution also increased [Ca2+]i. The amplitude of the increase was significantly smaller than that in the presence of extracellular Ca2+. These results suggested that depolarization induces Ca2+ mobilization via the Ca2+ influx and release from the Ca2+ stores in rat odontoblasts.