Characterization and gene expression of high conductance calcium-activatedpotassium 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 clas ses of ion channels have previously been identified in the odontoblast or p ulp 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 odo ntoblasts fully differentiated in vitro using the patch clamp technique and to investigate the HSLO gene expression encoding the alpha-subunit of thes e channels on odontoblasts in vivo. In inside-out patches, K-Ca channels we re identified on the basis of their K+ selectivity, conductance, voltage, a nd Ca2+ dependence. In cell-attached patches, these channels were found to be activated by application of a negative pressure as well as an osmotic sh ock, By reverse transcription-polymerase chain reaction, a probe complement ary to K-Ca alpha-subunit mRNA was constructed and used for in situ hybridi zation on human dental pulp samples. Transcripts were expressed in the odon toblast layer. The use of antibodies showed that the K-Ca channels were pre ferentially detected at the apical pole of the odontoblasts. These channels could be involved in mineralization processes. Their mechanosensitivity su ggests that the fluid displacement within dentinal tubules could be transdu ced into electrical cell signals.