Summary of whole-cell patch clamp currents with only Na+ or K+ as the major permeant ions. A) Bar graph of the conductances and B) currents at -100 mV in symmetrical Na+-rich solutions (B2, P2) and K+-rich solutions (B3, P3). C) Current-voltage (I-V) relationships of the Benzamil-sensitive current at steady state (near 300 ms). Benzamil-sensitive current was only observed in Na+ solutions. K+ currents were markedly smaller than Na+ currents.