Endocochlear potential and endolymphatic K⁺ changes induced by gap junction blockers

Objective - To examine the effects of gap junction blockers on the endocochlear potential (EP) and endolymphatic potassium concentration ([K ⁺]_e). Material and Methods - The EP and [K ⁺]_e were monitored using double-barreled ion-selective microelectrodes in the second turn of the guinea pig cochlea during perilymphatic perfusion. Results - When the perilymphatic scalae of the cochlea were perfused with artificial perilymph containing 10 mM n-heptanol the EP was decreased by -8.8±1.4 mV (n = 10), and this was accompanied by a decline in the [K⁺]_e of -6.7±2.1 mM (n = 6). Perilymphatic application of 10 mM hexanol also produced declines in both the EP and [K ⁺]_e. In control studies, perilymphatic perfusion with 10 mM ethanol showed no remarkable changes in either the EP or [K⁺] _e. Anoxia during perfusion with heptanol resulted in the generation of a negative EP, similar to the situation in controls. Conclusions - A decline in the EP together with a lowering of [K⁺]_e induced by long-chain n-alkanols, which act as gap junction blockers, may be explained by an interruption in potassium ion transport related to a gap junction dysfunction.