Abstract
Electrical resistance of scala media at the second turn of the guinea pig cochlea was measured while cochlear adenylate cyclase was activated by perilymphatic perfusion with 2 ± 10−4M forskolin. The electrical resistance decreased from the pre-forskolin value (6.36 ± 0.27 kω to 5.22 ± 0.33 kω, n = 5), while the endocochlear potential (EP) increased from the pre-forskolin value (70.2 ± 2.1 mV to 81.2 ± 2.8 mV, n = 5). The time course of the electrical resistance change was more rapid than that of the EP change but almost identical to the time course of the change in the CI− activity of the endolymph. The results suggest that the forskolin-induced decrease in the electrical resistance of the perilymph-endolymph barrier (presumably Reissner's membrane), and the consequent increase in CI− flux into the endolymph may trigger EP elevation.