The influence of calcium-free solutions upon permeability characteristics of the rabbit lens

Sodium, potassium and chloride content, potential difference and ⁸⁶Rb efflux rate constants were measured in rabbit lenses bathed in normal or calcium-free EGTA solution. The absence of calcium in the bathing solution resulted in a rapid depolarization of the lens potential, and a two-fold increase in the ⁶⁸Rb efflux rate. These changes were not due to the alteration of the ion distribution between the lens and its environment in the calcium-free solution, and the increase in the ⁶⁸Rb efflux rate could be explained on the basis of the depolarization alone. The magnitude of the calcium-free induced depolarization was not diminished when the lens active transport was inhibited by ouabain, but was significantly reduced when part of the sodium in the bathing solution had been replaced by sucrose. These observations suggested that one of the early effects of removal of calcium from the bathing solution is a rapid elevation of lens sodium permeability.