Current-voltage relationships in the crystalline lens

Abstract

1. Electrical coupling between the cells of the crystalline lens of the frog eye was studied using two intralenticular micro-electrodes, one to pass current and one to record potential. In most experiments, both electrodes were placed just inside the posterior surface of the lens at a depth of approximately 200 mum from the surface. Step functions of current were applied and the time course of the resulting change in voltage was measured at many different electrode separations. 2. The voltage change has both a fast component, which occurs only locally in the region close to the current passing micro-electrode, and a slow component, which is spatially uniform, independent of distance from the current micro-electrode. 3. This behaviour is predicted by an electrical model of a single large spherical cell, and so that model can be used to analyse our data. 4. The resistivity of the lens 'interior' (both cytoplasm and coupling resistivity) is 625 omega cm; the resistance of the lens 'membrane' is 2751 omega cm2. 5. The data and analysis help to reconcile discrepancies between previous measurements of the electrical properties of the lens and show clearly that there is substantial electrical coupling from cell to cell. The method should allow investigation of the role of electrical coupling in cataract formation in the crystalline lens.