Amiloride-sensitive sodium currents in identified taste cells of the frog

Abstract

Sodium ions occurring in food are thought to be detected, at least in part, through specific amiloride-sensitive, sodium channels (ASSCs) localized in taste receptor cells. Cells within taste buds are morphologically heterogeneous, and include taste receptor cells and other cells that could perform a support or even transduction role. It is not known whether subsets of the taste bud cells express ASSCs, and whether the properties of these channels are similar. By applying the patch-clamp technique to morphologically distinct cells, the supporting wing cells, isolated from the frog taste disk, I have found functional ASSCs that are moderately sensitive to amiloride (Ki 3-4 microM) and which are distinctly lower in affinity for amiloride than reported frog taste receptor cells (Ki 0.2 microM). These results support the hypotheses of the existence of distinct, functional ASSCs in different cell morphotypes, at least in frog taste organs.