Contribution of some anions and cations to potential difference in frog crystalline lens.

Abstract The posterior potential of frog lens has been studied with a microelectrode technique. The lens potential behaved predominantly as a K-electrode, and the slope of the potential for a tenfold change in [K]o, as the product [K]o · [Cl]o was kept constant, was in good agreement with 58 mV predicted from the Nernst equation at high [K]o. The permselectivity of lens membrane towards 90 m m monovalent cations was in the order K + > Rb + > Cs + > NH 4 + . The lens membrane was permeable not only to Cl − but also Br − , I − , NO 3 − , N 3 − , SCN − , ClO 3 − , BrO 3 − , and formate, but not to acetate, propionate, and aspartate. Na + was a much less contributive ion as compared with either K + or Cl − on the lens potential.