Chlorpromazine alters outer hair cell electromotility.
OBJECTIVE
Outer hair cells (OHCs) of the inner ear rapidly convert electrical gradients into mechanical force, enhancing cochlear sensitivity and frequency selectivity. We investigated the effect of chlorpromazine, an antipsychotic medication that alters membrane biomechanics, on OHC electromotility.


METHODS
Isolated guinea pig outer hair cells were perfused with chlorpromazine under whole-cell patch-pipette recording conditions. Electromotile responses were measured.


RESULTS
A dramatic, reversible, dose-dependent depolarization of voltage at peak capacitance (V(pkCm)) was seen with chlorpromazine treatment. The gain of the electromotile response was maximal near V(pkCm) both before and after chlorpromazine application. Unlike the 3 other agents that alter electromotility (salicylate, lanthanides, membrane tension), chlorpromazine did not change peak capacitance (Cm(pk)), which varies directly with maximal electromotile gain.


CONCLUSIONS
Chlorpromazine changes the membrane voltage at which OHCs exhibit maximal electromotile gain, without changing the magnitude of electromotile responses.


CONCLUSIONS
Chlorpromazine may diminish hearing thresholds or otoacoustic emissions in large doses.
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Bobby Ray Alford Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, Houston, TX, USA.
Zhao
H B
HB
Brownell
W E
WE
D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D002746:Chlorpromazine / Q000494:pharmacology*; D003051:Cochlea / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D005260:Female; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D012680:Sensitivity and Specificity
D002746:Chlorpromazine