Effect of calcium ion concentration on the permeability of the corneal endothelium.
The effect of free Ca2+ ion concentration on the integrity of the barrier function of the corneal endothelium was studied using the endothelial permeability to carboxyfluorescein (Pac) as a quantitative index according to the method of Araie. Paired rabbit corneas were isolated and mounted in a chamber. To serve as a control, one eye of each pair was perfused with a glucose-glutathione-bicarbonate solution at a Ca2+ concentration of 1.1 mEq, the other with a solution at various Ca2+ concentrations ranging from 0.23-1.1 mEq. The Pac ratio of a solution with a Ca2+ concentration of 0.38 mEq or higher to the control solution was close to unity, and the Pac ratio of a solution with a Ca2+ concentration of 0.33 mEq or lower to the control solution was significantly greater than unity. In a separate experiment, it was found that only slight swelling was seen when a solution with a Ca2+ concentration of 0.23 mEq or higher was used; significant swelling was seen with a solution of a Ca2+ concentration of 0.17 mEq or lower. The lowest free Ca2+ concentration needed for maintaining the barrier function of the corneal endothelium, 0.38 mEq, was found to be higher than that needed for maintaining the corneal thickness, 0.23 mEq.
Department of Ophthalmology, University of Tokyo School of Medicine, Japan.
M
M
Araie
K
K
Hamano
S
S
Eguchi
S
S
Matsumoto
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004728:Endothelium, Corneal / Q000378:metabolism*; D066298:In Vitro Techniques; D007477:Ions; D009994:Osmolar Concentration; D010477:Perfusion; D010539:Permeability; D011817:Rabbits
D007477:Ions; D002118:Calcium