Differential expression of potassium currents in Deiters cells of the guinea pig cochlea.

Among the supporting cells, Deiters cells are in intimate contact with outer hair cells (OHCs) in the inner ear. The aim of this study was to characterize the outward rectifying K+ current of Deiters cells in conjunction with cellular morphological characteristics. In the majority of cells, the K+ current had a biphasic inactivation kinetics (tau1 and tau2 were 2,735+/-90 (n=77) and 160+/-14 ms (n=72), respectively). The rapidly inactivating current component was more sensitive to Charybdotoxin (ChTx, 10 nM) block whereas the slowly inactivating current could be blocked more efficiently by tetraethylammonium (1 mM). All these point toward the existence of two distinct potassium channel types in these cells. Deiters cells attached to shorter OHCs had more voluminous, whereas those attached to longer OHCs had lanky cell bodies. The inactivation kinetics was slower in cells having corpulent cell bodies due to the increased proportion of the slowly inactivating current component (0.736+/-0.033, n=27) as compared to the one determined for lanky cells (0.522+/-0.023, n=36). The average peak K+ current was higher in Deiters cells connected to OHCs (5,417+/-541 pA, n=40) than in isolated ones (3,527+/-410, n=37). Deiters cells having different cell shapes and showing different K+ channel expression may contribute to the active mechanism of the cochlea to various degrees.