Properties of Transient K+ Currents and Underlying Single K+ Channels in Rat Olfactory Receptor Neurons

Lynch, JW and Barry, PH (1991) Properties of Transient K+ Currents and Underlying Single K+ Channels in Rat Olfactory Receptor Neurons. Journal of General Physiology, 97 5: 1043-1072. doi:10.1085/jgp.97.5.1043

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Author Lynch, JW
Barry, PH
Title Properties of Transient K+ Currents and Underlying Single K+ Channels in Rat Olfactory Receptor Neurons
Journal name Journal of General Physiology   Check publisher's open access policy
ISSN 0022-1295
Publication date 1991-05-01
Year available 1991
Sub-type Article (original research)
DOI 10.1085/jgp.97.5.1043
Open Access Status File (Publisher version)
Volume 97
Issue 5
Start page 1043
End page 1072
Total pages 30
Place of publication NEW YORK
Publisher ROCKEFELLER UNIV PRESS
Language eng
Abstract The transient potassium current, I(K)(t), of enzymatically dissociated rat olfactory receptor neurons was studied using patch-clamp techniques. Upon depolarization from negative holding potentials, I(K)(t) activated rapidly and then inactivated with a time course described by the sum of two exponential components with time constants of 22.4 and 143 ms. Single-channel analysis revealed a further small component with a time constant of several seconds. Steady-state inactivation was complete at -20 mV and completely removed at -80 mV (midpoint -45 mV). Activation was significant at -40 mV and appeared to reach a maximum conductance at +40 mV (midpoint -13 mV). Deactivation was described by the sum of two voltage-dependent exponential components. Recovery from inactivation was extraordinarily slow (50 s at -100 mV) and the underlying processes appeared complex. I(K)(t) was reduced by 4-aminopyridine and tetraethylammonium applied externally. Increasing the external K+ concentration ([K+]o) from 5 to 25 mM partially removed I(K)(t) inactivation, usually without affecting activation kinetics. The elevated [K+]o also hyperpolarized the steady-state inactivation curve by 9 mV and significantly depolarized the voltage dependence of activation. Single transient K+ channels, with conductances of 17 and 26 pS, were observed in excised patches and often appeared to be localized into large clusters. These channels were similar to I(K)(t) in their kinetic, pharmacological, and voltage-dependent properties and their inactivation was also subject to modulation by [K+]o. The properties of I(K)(t) imply a role in action potential repolarization and suggest it may also be important in modulating spike parameters during neuronal burst firing. A simple method is also presented to correct for errors in the measurement of whole-cell resistance (R(o)) that can result when patch-clamping very small cells. The analysis revealed a mean corrected R(o) of 26 G-OMEGA for these cells.
Keyword Human Lymphocytes-T
Potassium Channels
Outward Current
Patch-Clamp
Sensory Neurons
Membrane Currents
Nodose Neurons
Guinea-Pig
Cells
Nerve
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: ResearcherID Downloads - Archived
 
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