Internally perfused axons: effects of two different anions on ionic conductance.

Voltage-clamizped giant axons of squid, internally perfused with potassiumt chloride solutions, showed reduced initial transient memnbrane conductance to voltage and increased overall (leakage) conductance. Unclamtped axons showed reduced action and resting potentials. Ionic conductances and memtbrane potentials were maintained or restored by perfusion with potassiuwn fluoride solutions. As much as 90 percent of internal fluoride could be replaced with chloride without alterationt of normal properties of membrane.