FIGURE 5.

Concentration dependence of DEA block of single sodium channels, when either bound or unbound by R13E. Current traces recorded from a single BTX-activated rat skeletal muscle sodium channel under control conditions (symmetrical 200 mM NaCl, 10 mM MOPS, pH 7.0), and after addition of 33 μM external R13E, then with the further addition of 5, 10, or 15 mM internal DEA. The holding voltage in this and all other experiments is +50 mV. Solid lines indicate the closed level (C), and, for reference, the dotted lines approximate the open (O) level (R13E not bound).