The influence of external potassium ions upon lens conductance characteristics investigated using a voltage clamp technique

An intracellular voltage clamp technique for the lens is described. Using this technique, it was possible to describe directly the conductance-voltage relationship of the lens over a wide range of lens potentials. The influence of potassium-rich solutions on lens conductance and ⁴²K efflux rate was examined under conditions where the voltage clamp prevented changes in the lens potential. Under these conditions, potassium-rich solutions caused a reduction in lens conductance and a fall in the ⁴²K efflux rate. These observations suggest that, at the resting potential, potassium-rich solutions influence conductance by decreasing lens potassium permeability. However, when the lens is not voltage clamped, the reduction of lens conductance is masked because the depolarization of lens potential increases the voltage-dependent conductance component, leading to an overall increase in the conductance of the lens.