The properties of bovine lens membranes measured by a conventional double‐chamber method

1. When the bovine lens was mounted in a divided chamber, an asymmetry potential of 4·3 mV (anterior face positive) was measured across the lens and values of 0·48 and 0·60 were obtained for P_Na/P_K of the anterior and posterior faces respectively. 2. The half‐times for the depolarization of the anterior and posterior face potentials on increasing the external K concentration were 20 and 14 min respectively compared to less than 2 min for the corresponding change determined previously from the totally immersed lens. 3. The electrical resistance of the anterior surface was significantly smaller than that of the posterior and both resistances were much smaller than the value previously obtained from the bovine lens immersed in solution. 4. The K permeability of the anterior surface, measured by ⁴²K efflux experiments, was greater than the value for the posterior surface and both were again very much higher than the value obtained for the totally immersed lens. 5. The discrepancies between the present double‐chamber preparation and the data obtained previously can be explained if it is assumed that the capsule provides a short‐circuit pathway between the chamber port and the lens membranes. As the capsule is thicker at the anterior face, the short circuit there would be greater and this may explain many previously observed ‘asymmetry’ properties for the lens.