POTASSIUM CURRENTS IN CELLS DERIVED FROM HUMAN DENTAL-PULP

Patch-clamp recording methods were used to monitor ion currents in tis sue-cultured cells derived from human dental pulp. Recordings were mad e in excised, outside-in or whole-cell patches. In single-channel expe riments, the majority of patches contained a high-conductance (approx. 140-180 pS) K+-selective ion channel. The probability of the channel being in an open state was dependent on membrane potential, internal c alcium and negative pressure applied to the cell membrane. Whole-cell recordings were consistent with these findings; in response to step-wi se depolarizations of the cell membrane, most displayed a family of ou twardly rectifying, barium-sensitive currents. In addition, a number o f patches contained a second class of potassium channel of intermediat e (approx. 85-100 pS) conductance, which was largely voltage insensiti ve and independent of calcium concentration. These results suggest tha t pulp cells contain a high-conductance potassium channel which probab ly underlies the outwardly rectifying current found at the whole-cell level. Further, the existence of mechanosensitive channels in these ce lls raises the possibility that the response to mechanical perturbatio n of dental pulp may be mediated, in part, by direct effects on odonto genic cells.