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Transient potassium currents in avian sensory neurons
S K Florio1, C D Westbrook, M R Vasko
1Department of Pharmacology, University of Texas Southwestern Medical School, Dallas 75235.
Journal of Neurophysiology
|April 1, 1990
Summary
Transient potassium currents in chick dorsal root ganglion cells were studied. These currents are important for early outward current during depolarizations from hyperpolarized potentials.
Area of Science:
- Neuroscience
- Electrophysiology
- Ion Channel Physiology
Background:
- Dorsal root ganglion (DRG) cells are crucial for sensory information transmission.
- Voltage-activated potassium currents play a vital role in neuronal excitability.
- Understanding transient potassium currents is key to deciphering neuronal signaling.
Purpose of the Study:
- To investigate the properties of voltage-activated transient potassium currents in chick DRG cells.
- To characterize the kinetics and conductance of these transient potassium channels.
- To determine the contribution of transient outward currents to DRG cell electrical activity.
Main Methods:
- Patch-clamp technique (whole-cell and cell-attached configurations) was employed.
- Cells were freshly dispersed and cultured chick dorsal root ganglion (DRG) cells.
- Ionic currents were recorded under controlled voltage-clamp conditions.
Main Results:
- A transient outward potassium current component was identified, prominent in freshly dispersed cells.
- This transient current inactivated rapidly (time constants 8-26 ms) after hyperpolarizing prepulses.
- Single-channel analysis revealed transiently opening channels with conductances of 18-32 pS (Na+) and 43 pS (K+).
Conclusions:
- Transient potassium channels mediate the observed transient outward current in DRG cells.
- This current contributes significantly to early outward currents from hyperpolarized potentials.
- The transient current's prominence decreases with time in cell culture, suggesting channel modulation or loss.