Supporting cells of the hearing organ are studied mostly in young and still deaf rodents. The receptors of the purinergic system is spread in the supporting cells and their roles in spontaneous activity during the development has been recognized, but our knowledge about the presence and role in older mice is much sparse.We have investigated the ATP induced Ca2+ transients with both experimental and modeling approaches.ATP-evoked Ca2+ responses were measured in Deiters’ (DCs), Hensen’s (HCs) and Claudius’ cells (CCs) in the BALB/c mouse hemicochlea preparation (from 14 days old to 21 days old). The evoked Ca2+ transients have different characteristics (in duration and amplitude) depending on the cell-type indicating different receptors and Ca2+ handling mechanisms.We have set up a mathematical model to simulate the mechanisms of the ATP-induced responses (activate both the intracellular stores and the extracellular influx of Ca2+ through the ionotropic P2X receptors).Our model was emulated reliably the Ca2+ transients measured by the functional imaging. The models suggest that the parameters of Ca2+ removing mechanism (especially in parameters of SERCA function) and the P2X receptors have the biggest differences among the cells. The results indicated by the model are suitable to initiate new experiments to decipher the precise role of the intracellular Ca2+ regulation in DCs, HCs and CCs in the function of hearing and hearing sensitivity. This study was supported by the strategic research fund of the University of Veterinary Medicine Budapest (Grant No. SRF-001.)