The delayed rectifier, IKI, is the major conductance in type I vestibular hair cells across vestibular end organs.
Hair cells were dissociated from the semicircular canal, utricle, lagena and saccule of white king pigeons. Type I hair cells were identified morphologically based on the ratios of neck width to cuticular plate width (NPR < 0.72) as well as neck width to cell body width (NBR < 0.64). The perforated patch variant of the whole-cell recording technique was used to measure electrical properties from type I hair cells. In voltage-clamp, the membrane properties of all identified type I cells were dominated by a predominantly outward potassium current, previously characterized in semicircular canal as IKI. Zero-current potential, activation, deactivation, slope conductance, pharmacologic and steady-state properties of the complex currents were not statistically different between type I hair cells of different vestibular end organs. The voltage dependence causes a significant proportion of this conductance to be active about the cell's zero-current potential. The first report of the whole-cell activation kinetics of the conductance is presented, showing a voltage dependence that could be best fit by an equation for a single exponential. Results presented here are the first data from pigeon dissociated type I hair cells from utricle, saccule and lagena suggesting that the basolateral conductances of a morphologically identified population of type I hair cells are conserved between functionally different vestibular end organs; the major conductance being a delayed rectifier characterized previously in semicircular canal hair cells as IKI.
Ricci
A J
AJ
Department of Otolaryngology , MRB, Rt. J-63, University of Texas Medical Branch at Galveston, Galveston TX 77555-1063, USA.
Rennie
K J
KJ
Correia
M J
MJ
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D010856:Columbidae; D004553:Electric Conductivity; D004594:Electrophysiology; D018069:Hair Cells, Vestibular / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D006706:Homeostasis; D007700:Kinetics; D008959:Models, Neurological; D011188:Potassium / Q000502:physiology*
D015761:4-Aminopyridine; D011188:Potassium