[Characteristics of outward potassium currents of outer hair cell isolated from the guinea pig cochlea].
OBJECTIVE
To study the normal values and characteristics of potassium currents (Ik) of outer hair cell (OHC) isolated from the guinea pig cochlea.


METHODS
With the patch-clamp whole cell recording technique and several supplementary methods, the Ik potassium tail current (Iktail) and reverse potential were recorded under the conditions of the various intra and extracellular solutions and various command voltage stimuli.


RESULTS
Ik possessed evident voltage and time-dependence. The peak current appeared within 20 ms. The average activated potential was approximately -32.7 mV. Ik increased fastestly and greatestly in the voltage range from the activating voltage to 0 mV, and it approached saturation approximately at 40 mV. In normal status, no distinct "rundown phenomenon" of Ik appeared. When 10 mmol/L KCl was put in extracellular solution, Ik would increased. Nevertheless, when K+ was substituted by Cs+ in the intracellular solution, Ik would disappear. The reversal potential, -64.0 mV in average approximately, could be measured by means of Iktail. Furthermore, by means of slope command voltage stimuli, the processes of Ik activation, increment or decrement and saturation could be observed.


CONCLUSIONS
As showing by the above described features, Ik possessed the characteristics of both an inward rectifier and rapid element of a delay rectifier, which would play important role in frequency tuning, mechanic-electrical transduction, maintenance of resting potential and excitement in OHC.
Liang
Y
Y
Department of Otolaryngology, Union Hospital, Tongji Medical University, Wuhan 430022.
Zhong
N
N
D000818:Animals; D003051:Cochlea / Q000502:physiology*; D005260:Female; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*
D015221:Potassium Channels