Objectives: In the phospholipase-C signaling system, Ca²⁺ is mobilized from intracellular Ca²⁺ stores by an action of inositol 1,4,5-trisphosphate (IP₃). The depletion of IP₃-sensitive Ca²⁺ stores activates a Ca²⁺ influx pathway at the plasma membrane known as store-operated Ca²⁺ entry (SOCE). In this study, we investigate the characteristics of the SOCE, the role of IP₃ receptors in the SOCE activation and IP₃-mediated Ca²⁺ mobilizations in odontoblasts in rat dental pulp slice preparations. Methods: A Fura-2 fluorometric technique was utilized to monitor the change in intracellular Ca²⁺ concentration ([Ca²⁺]i). Results: In the absence of extracellular Ca²⁺, an application of a sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) inhibitor, thapsigargin (TG), evoked a transient rise in [Ca²⁺]i. After the TG-treatment to deplete the store, the subsequent addition of Ca²⁺ resulted in a rapid rise in [Ca²⁺]i, indicative of SOCE. The [Ca²⁺]i increase due to SOCE was dependent on the extracellular Ca²⁺ concentration with apparent dissociation constant of 1.29 mM and no SOCE was evoked in the absence of TG-treatment. In TG-treated odontoblast, an activation of SOCE was abolished by a membrane permeable IP₃ receptor inhibitor, 2-aminoethoxydiphenyl borate (2-APB). An application of 2-APB or La³⁺ (a potent blocker of SOCE) while SOCE was maximally active resulted in rapid terminations of SOCE. The inhibitory effect of La³⁺ on SOCE was dependent on the La³⁺ concentration with half-maximal inhibitory concentration of 26µM. In the absence of extracellular Ca²⁺, the phospholipase-C-coupled receptor agonists, carbachol and bradykinin, produced rapid increases in [Ca²⁺]i, which were inhibited by 2-APB. Conclusions: These results indicate that IP₃-mediated signaling pathway activates store-operated Ca²⁺ channels in odontoblasts. (Supported by Grant-in-Aid for Scientific Research (No. 13771103) from the Ministry of Education, Culture, Sports, Science and Technology of Japan)