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. 2008 Jul 25;95(9):4266–4276. doi: 10.1529/biophysj.108.138271

FIGURE 2.

FIGURE 2

Block of a single sodium channel by TPrA. [TprA] dependence in periods where the channel is R13E-bound, or R13E-free. Current traces were recorded from a single BTX-activated, rat skeletal muscle sodium channel under control conditions (top trace: symmetrical 200 mM NaCl, 10 mM MOPS, pH 7.0), and after addition of 33 μM external R13E (second trace), and then with the further addition of 5, 7.5, or 10 mM internal TPrA (bottom three traces). The holding voltage in this and all other experiments is +50 mV. Solid lines indicate the closed level (C), and dotted lines indicate the open (O) level (R13E unbound). The long segments showing the channel opening to an intermediate level represent periods during which R13E is bound, partially blocking current through the channel. These events are seen in the first part of the second trace, and the latter sections of the bottom three traces.