The effects of amiloride, ouabain and osmolality on sodium transport across bovine cornea

Area of Science:

• Ophthalmology
• Physiology
• Biophysics

Background:

• The cornea's electrical properties are crucial for its function.
• Understanding ion transport mechanisms is key to corneal physiology.

Purpose of the Study:

• To investigate the electrical parameters of the bovine cornea.
• To elucidate the role of sodium transport in corneal electrophysiology.
• To characterize the effects of amiloride and ouabain on corneal electrical properties.

Main Methods:

• Measurement of transcorneal potential difference and short-circuit current.
• Variations in bathing solution osmolality, temperature, pH, and sodium concentration.
• Application of amiloride and ouabain.
• Calculation of cellular and paracellular pathway resistances.

Main Results:

• Transcorneal potential difference is the sum of transendothelial and transepithelial potentials.
• Amiloride completely and reversibly inhibited epithelial potential difference and short-circuit current (Ki = 2 x 10(-6) mol/l).
• Transcorneal electrical resistance increased by 28 +/- 8% with amiloride.

Conclusions:

• The epithelium is the primary site of amiloride-sensitive sodium transport.
• An equivalent electrical circuit model for sodium transport across the bovine cornea was proposed.
• The study provides insights into corneal ion transport and electrical resistance.