HYPOSMOTIC SMELLING INDUCES MAGNITUDE AND GAIN CHANGE IN THE ELECTROMOTILE PERFORMANCE OF ISOLATED OUTER HAIR-CELLS

OHCs were inserted into a partitioning microchamber. Reversible swelli ng was induced by hyposmotic incubation medium (270 mosm.kg H2O-1). Th e transfer curve of electromotility was measured by stimulating the OH Cs with a series of brief (2.5 ms) square-pulses with both polarities and graded magnitudes. Response magnitude and gain of electromotility were increased in swollen OHCs. On the basis of their electromotile pe rformance-characteristics, swelling appeared to depolarize the OHCs. T ransition from contraction dominated asymmetry of motility was observe d towards a symmetric response. Depolarization, by itself cannot expla in the gain and magnitude increase. Acetylcholine (ACh) responsiveness of swollen OHCs preserves the pre-challenged pattern: ACh further inc reases gain and magnitude.