Membrane excitability of wing and rod cells in frog taste discs following denervation.

The frog tongue has a disc-shaped taste organ (taste disc) on the top of fungiform papillae. The taste disc contains two types of cells, wing cells with a sheet-like apical process and rod cells with a rod-like apical process. Both wing and rod cells can produce action potentials. Unlike the taste buds of mammals, frog taste discs do not degenerate over a long period after denervation. Here we report that the shapes of wing and rod cells isolated from taste discs in the bullfrog (Rana catesbeiana) remained unchanged 1 month after cutting bilateral glossopharyngeal nerves. By applying the whole cell patch-clamp technique to isolated wing and rod cells, we found voltage-dependent inward currents and outward currents and action potentials in denervated frogs as seen in normal frogs. These results suggest that the maintenance of morphological integrity and electrical excitability of taste cells does not require a nerve supply in frogs.