Whole-cell K+ currents in isolated rabbit corneal epithelial cells

Area of Science:

• Cellular physiology
• Ion channel function
• Ocular biology

Background:

• The corneal epithelium is crucial for maintaining ocular surface integrity.
• Understanding ion transport mechanisms is vital for comprehending corneal physiology and disease.
• Potassium (K+) channels play significant roles in cellular excitability and transport.

Purpose of the Study:

• To characterize the membrane currents in rabbit corneal epithelial cells.
• To identify the primary ion responsible for these currents.
• To investigate the properties and modulation of these currents.

Main Methods:

• Whole-cell patch clamp technique was employed on enzymatically isolated rabbit corneal epithelial cells.
• Extracellular potassium (K+) concentration was systematically varied.
• Membrane currents were recorded during voltage step changes.
• Effects of cesium (Cs+) and barium (Ba2+) ions on currents were assessed.

Main Results:

• Rectangular membrane currents with fluctuations were observed, diminishing near the zero-current potential.
• The reversal potential in 5.4 mM K+ was -57.8 mV and shifted positively with increasing extracellular K+ (41.0 mV/decade).
• Increasing extracellular K+ caused depolarization of the resting potential.
• Whole-cell currents were significantly inhibited by Cs+ and Ba2+.

Conclusions:

• Potassium (K+) ions are the major charge carriers contributing to the measured membrane currents in rabbit corneal epithelial cells.
• The observed current characteristics are consistent with the activity of K+ channels.
• These findings provide insights into the electrophysiological properties of the corneal epithelium.