Ionic transport across corneal endothelium.

Area of Science:

• Ophthalmology
• Corneal Physiology
• Cellular Biology

Background:

• The corneal endothelium maintains ocular clarity and intraocular pressure through active transport processes.
• Understanding ion transport mechanisms is crucial for managing corneal edema and related pathologies.

Purpose of the Study:

• To investigate the active potential difference across the bovine corneal endothelium.
• To elucidate the underlying mechanisms of ion transport, particularly sodium (Na+), across this tissue.

Main Methods:

• In vitro measurements of the active potential difference across the bovine corneal endothelium.
• Experiments conducted under varying conditions: temperature, pH, osmolality, and salt compositions.
• Utilized identical or different solutions on either side of the corneal membrane.

Main Results:

• Experimental data support a model of active sodium transport into the intercellular cleft.
• Observed potential differences were consistent across varied experimental conditions.
• Evidence suggests a specific mechanism for sodium ion re-entry into endothelial cells.

Conclusions:

• Sodium is actively transported into the intercellular cleft of the bovine corneal endothelium.
• A proposed model suggests electroneutral re-entry of Na+ into cells via coupled co-transport with carbonate.
• Carbonate is derived from bicarbonate present in the surrounding solution, highlighting a novel transport pathway.