Characterization and gene expression of high conductance calcium-activated potassium channels displaying mechanosensitivity in human odontoblasts

Odontoblasts form a layer of cells responsible for the dentin formation and possibly mediate early stages of sensory processing in teeth. Several classes of ion channels have previously been identified in the odontoblast or pulp cell membrane, and it is suspected that these channels assist in these events. This study was carried out to characterize the K-Ca channels on odontoblasts fully differentiated in vitro using the patch clamp technique and to investigate the HSLO gene expression encoding the alpha-subunit of these channels on odontoblasts in vivo. In inside-out patches, K-Ca channels were identified on the basis of their K+ selectivity, conductance, voltage, and Ca2+ dependence. In cell-attached patches, these channels were found to be activated by application of a negative pressure as well as an osmotic shock, By reverse transcription-polymerase chain reaction, a probe complementary to K-Ca alpha-subunit mRNA was constructed and used for in situ hybridization on human dental pulp samples. Transcripts were expressed in the odontoblast layer. The use of antibodies showed that the K-Ca channels were preferentially detected at the apical pole of the odontoblasts. These channels could be involved in mineralization processes. Their mechanosensitivity suggests that the fluid displacement within dentinal tubules could be transduced into electrical cell signals.