Depolarization-induced Intracellular Free Calcium Concentration Increases Show No Desensitizing Effect in Rat Odontoblasts

抄録

Odontoblasts play an important role in the transduction of the sensory signals underlying dentinal pain. Transmembrane voltage-independent Ca²⁺ influx in odontoblasts has been well described. Voltage-dependent Ca²⁺ influx has also been reported, but its biophysical properties remain unclear. The aim of the present study was to investigate the desensitizing effect of voltage-dependent Ca²⁺ influx in rat odontoblasts by measuring depolarization-induced intracellular free Ca²⁺ concentrations ([Ca²⁺ ]_i ). Odontoblasts on dental pulp slices from newborn rats were acutely isolated and [Ca²⁺ ]_i measured by using fura-2 fluorescence. Repeated application of extracellular high-K⁺ solution (50 mM), which induces membrane depolarization-elicited repeated and transient increases in [Ca²⁺ ]_i in the presence of extracellular Ca²⁺. Increases in depolarization-induced [Ca²⁺ ]_i showed no significant desensitizing effect (p >0.05; Friedman test). These results suggest that odontoblasts express a voltage-dependent Ca²⁺ influx pathway with no desensitizing properties.