Effects of calcium channel blockers on rabbit corneal endothelial function

The effects of calcium channel antagonists and agents that alter intracellular Ca2+ mobilization on corneal endothelial function have been examined. All experiments, except where specifically designated, were performed in the continuous presence of extracellular Ca2+. Verapamil (at 50 μM) increased the swelling rate of corneas bathed in normal Ringer solution whereas nifedipine and diltiazem (both up to 100 μM) were without effect. The nifedipine analog nisoldipine caused corneal swelling at 10 μM and 50 μM but nimodipine was without effect. When briefly exposed to a Ca2+-free solution corneal swelling was enhanced after subsequent exposure to 50 μM verapamil in normal Ringer but not after 50 μM diltiazem in normal Ringer, indicating that Ca2+ entry from the bathing solution into the cell was important and was apparently impeded by verapamil. Cadmium (0.6 and 1 mM) but not nickel (up to 250 μM) caused swelling of corneas bathed in normal Ringer. A Ca2+ channel agonist, BAY-K-8644, alone did not influence ...