Figure 4.

CDDP competes with amiloride, lessening the inhibitory effects of amiloride on ENaC. (A) Overlay of typical macroscopic current traces from a representative CHO cell expressing mENaC before and after treatment, with (0.2–10 µM) amiloride in the presence (dashed lines) and absence (full lines) of 10 µM of CDDP. Currents elicited by voltage ramps were stepped from a holding potential of 40 mV to 60 mV and ramped to −100 mV. (B) Summary graph of (n = 3–5 for each amiloride concentration) experiments showing concentration-dependent effects of amiloride on mENaC in the absence (black circles, full line) and presence (white boxes, dashed line) of 10 µM of CDDP. Exposure to CDDP reduced the maximal inhibition percentage of amiloride and caused a dextral displacement of the amiloride inhibition curve.