Abstract
Although actin has been localized in hair cells, evidence for its role in intact cochlear preparations is lacking. The present study was undertaken to test the hypothesis that actin is involved in cochlear function (e.g., the active process) by observing the effects of a potent filamentous muscle actin inhibitor, cytochalasin D, on evoked cochlear potentials. Perilymphatic spaces of guinea pig cochlea were perfused with Ringer solutions containing either cytochalasin D (10−8 to 10−5 M) or DMSO (0.00005% to 0.05%) at a rate of 2.5 μ1/min for 10 min [Bledsoe et al., Hear. Res. 4, 109 (1981)]. Immediately after each period of perfusion, the compound action potential (CAP), cochlear microphonics (CM), and summating potential (SP) evoked by 10‐kHz tone bursts of varying intensity were recorded from an electrode in the basal turn. Cytochalasin D suppressed CAP and SP in a dose‐dependent fashion but did not affect CM. DMSO had no effect. These results provide pharmacological evidence that actin is involved in cochlear function—possibly the active mechanical process of the organ of Corti. [Supported by NSF, NINCDS, the Southern Hearing and Speech Foundation, Kresge Foundation, and the LA Lions Eye Foundation.]
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