Figure 5

Whole-cell patch clamp currents with only Na⁺ or NMDG⁺ as the major permeant ions. The compositions of the bath perfusates are indicated by the horizontal bars and the colors of the bars are identical to the colors in the corresponding graphs. A) Representative continuous trace recordings in the presence and absence of Benzamil (1 μM) in Na⁺-rich bath and 15 mM Na⁺ pipette solutions (B2, P4) and NMDG⁺-rich bath and 15 mM Na⁺ pipette solutions (B5, P4). Voltage step protocols were applied every 5.3 seconds with holding at 0 mV and steps from +100 mV to -100 mV in 20 mV decrements. Individual step responses are shown in the lower panels and their locations within the continuous trace are indicated by the numbers in parentheses. B) Summary bar graph of the currents at -100 mV in Na⁺-rich bath (B2) with Benzamil (1 μM) and NMDG⁺-rich bath solutions (B5). C) Representative current-voltage (I-V) relationships of the whole cell currents in the presence and absence of Benzamil (1 μM) in Na⁺-rich bath and 15 mM Na⁺ pipette solutions (B2, P4) and NMDG⁺-rich bath and 15 mM Na⁺ pipette solutions (B5, P4) at steady state (near 200 ms). NMDG⁺ reduced the inward current (-100 mV) by the same amount as did benzamil, and there was no difference between outward current (+100 mV) in NMDG⁺- and Na⁺-rich baths (B5 and B2)