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Potassium currents in chick sensory neurons change with development.
1Department of Physiology, University of Nevada School of Medicine, Reno 89557.
Brain Research. Developmental Brain Research
|June 1, 1990
Summary
This study investigated voltage-gated potassium currents in developing chick sensory neurons. Potassium current inactivation varied with age, increasing significantly at embryonic day 14 and showing greater cell-to-cell variability in older chicks.
Area of Science:
- Neuroscience
- Developmental Biology
- Electrophysiology
Background:
- Sensory neurons in the dorsal root ganglia are crucial for transmitting sensory information.
- Voltage-gated ion channels, particularly potassium channels, play a vital role in neuronal excitability and function.
- Understanding the developmental changes in these currents is essential for comprehending nervous system maturation.
Purpose of the Study:
- To investigate the developmental changes in voltage-gated potassium currents in sensory neurons from embryonic and hatched chicks.
- To characterize the inactivation properties of these currents across different developmental stages.
- To correlate observed electrophysiological changes with neuronal maturation.
Main Methods:
- Whole-cell voltage-clamp recordings were performed on sensory neurons isolated from chick dorsal root ganglia at various embryonic (E8, E10, E14, E18) and post-hatch stages.
- Inward and calcium-activated currents were inhibited using tetrodotoxin, absence of added calcium, and intracellular EGTA.
- Potassium currents were analyzed for activation thresholds, inactivation during depolarizing steps, and changes in current amplitude following conditioning voltage pulses.
Main Results:
- Potassium currents were consistently activated by depolarizations positive to -40 mV across all studied ages.
- Outward current inactivation during short depolarizations (50-100 ms) was relatively stable but showed a transient increase at E14.
- Age-dependent changes in inactivation were evident with longer conditioning pulses, where older neurons exhibited greater inactivation of both early and late potassium currents, with increased cell-to-cell variability.
Conclusions:
- Voltage-gated potassium current inactivation properties undergo significant developmental changes in chick sensory neurons.
- These changes, particularly increased inactivation and variability in older embryos and hatched chicks, coincide with neuronal maturation and functional establishment.
- The findings provide insights into the electrophysiological remodeling of sensory neurons during development.