Potassium currents underlying the oscillatory response in hair cells of the goldfish sacculus.
1. Ionic currents underlying the oscillatory response of membrane potential were studied in oscillatory-type hair cells isolated from the goldfish sacculus with the whole-cell recording method using a patch pipette. 2. Bath application of 4-aminopyridine (4-AP; 10 mM) reversibly produced moderate depolarization of the resting potential along with complete suppression of the oscillatory response. Sustained injection of a small depolarizing current also suppressed the oscillatory response. 3. A 4-AP-sensitive atypical A-type K+ current which had a high threshold voltage for inactivation (IA(H)) was found to be a major outward current underlying the oscillatory response. 4. IA(H) was activated with a time constant of 0.4-10 ms and was inactivated slowly with a time constant of 0.6-2 s. IA(H) activation and inactivation occurred mostly at membrane potentials more positive than -70 mV. 5. There was a clear correlation between activation speed of IA(H) and the frequency of pulse-evoked oscillation. A 'hump'-type response was produced in about one-quarter of the oscillatory-type hair cells.
Sugihara
I
I
Department of Physiology, Tokyo Medical and Dental University School of Medicine, Japan.
Furukawa
T
T
D015761:4-Aminopyridine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D006054:Goldfish; D006198:Hair Cells, Auditory / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D002118:Calcium