Figure 2.

The difference current at 40 mV largely represents LP I_A. A, A residual current remains when LP I_A is blocked with 4 mm 4AP. Difference current traces elicited by a 40 mV test pulse from a single LP sequentially superfused with saline containing TTX followed by TTX + 4AP. A small residual net outward current remained when I_A was blocked. Calibration: 100 nA, 100 ms. B, The residual current is not regulated by activity. The experiments diagrammed in Figure 3A were performed in 4AP. Changes in duty cycle did not alter the residual current.