[Mechanical stimulation of isolated outer hair cells as a test system. Inhibition of transduction by streptomycin treatment].

Deflection of the hair bundle of isolated outer hair cells from the guinea pig cochlea can induce a receptor potential. Outer hair cells from the third and fourth turns of the guinea pig cochlea were isolated according to the method described by Zenner et al. Cells were maintained in Hank's balanced salt solution at room temperature. The whole cell potential was measured by the patch-clamp technique with soda glass capillaries (resistance 3-5 M omega) filled with KCl-Ringer solution. After compensation for the junction potential the stable resting potential of 46 cells was -63 mV +/- 5 mV. The hair bundle was deflected sinusoidally, with amplitudes ranging from 6 degrees to a maximum of 31 degrees in the positive direction (i.e., in the direction of the longest stereocilium). The stimulus was a piezo-driven glass capillary with an opening diameter of 5 microns. This mechanical stimulation induced in 33% of all stimulated cells (n = 46) a receptor potential response of 2.1 +/- 1.4 mV (maximally 5.5 mV). Deflection of the hair bundle in the opposite direction led to no change in the membrane potential, i.e. the cells were not hyperpolarized (minimal resolution 0.5 mV). Since the resting potential of the cells was more positive than the potassium equilibrium potential under our experimental conditions, the receptor current was most likely mediated by an influx of Na+ ions into the cell. The receptor potential response could be completely and reversibly blocked by the addition of dihydro-streptomycin.(ABSTRACT TRUNCATED AT 250 WORDS)