MEMBRANE-PROPERTIES OF 2 TYPES OF BASAL CELLS IN NECTURUS TASTE-BUDS

Necturus taste buds contain two types of basal cells: presumptive stem cells and Merkel-like basal cells. Both types of basal cells are smal l round cells located at the base of the taste bud, indistinguishable from each other with light microscopy. However, with electron microsco py, autoradiography, or immunocytochemistry, these two types of basal cells can be easily distinguished. We isolated basal cells from taste buds, characterized their voltage-dependent currents using gigaseal wh ole-cell recordings, and processed the cells for electron microscopy o r immunocytochemistry. We were able to distinguish two cell types elec trophysiologically and to correlate cell type with membrane properties . Isolated Merkel-like basal cells had several voltage-activated curre nts: transient, TTX-sensitive, inward Na+ current; sustained, saturati ng outward K+ current; and slowly inactivating inward Ca2+ current. Th ese currents are similar to those observed in taste receptor cells. In contrast, presumptive stem cells from Necturus taste buds only had ou tward K+ currents.