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

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.