[Study of electrophysiological properties of large conductance K(+)-channels in outer hair cells from the guinea pig with patch-clamp technique].
The basic electrophysiological characteristics of large conductance K(+)-channels in the basolateral cell membrane of outer hair cells (OHC) from the guinea pig cochlea were studied with patch-clamp technique. Acutely isolated OHC preparations were obtained by enzymatic digestion and excised patches were made in cell-attached configuration to record single-channel currents led by patch-clamp micropipette and fed to patch-clamp amplifier. Data were sampled and analyzed on-line with a computer. The result showed that the typical properties of single channels of large conductance K(+)-channels were: 1. The channel was activated by depolarization of membrane and it showed a marked voltage-dependence. The channel had a unitary conductance of about 133 pS and the channel current reversed at about -30mV under asymmetrical K+ concentration gradient. 2. Tetraethylammonium (TEA, > 10 mmol/L), a potassium channel blocker, dose-dependently abolished the outward current. 3. The open probability (Po) and mean open time of this channel was markedly increased with elevation of cytoplasmic Ca2+ concentration. These results suggest that a population of voltage-dependent and Ca(2+)-activated K+ channel exists in the basolateral membrane of OHC of the guinea pig; it is characterized by a very high unitary conductance and high sensitivity to Ca2+ and is blocked by K+ channel blocker. This work provided valuable basic materials for further study on the regulation and drug influence of the type of single channels.
Tang
Y
Y
Department of Otolaryngology, First Affiliated Hospital, Chengdu.
Lin
D
D
Liang
C
C
Zeng
X
X
He
J
J
Liu
Z
Z
D000818:Animals; D004553:Electric Conductivity; D004594:Electrophysiology; D005260:Female; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D008297:Male; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects*; D019789:Tetraethylammonium / Q000494:pharmacology*
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D019789:Tetraethylammonium