Figure 8. The ionic basis of I_CAN.

A, preBötC neuron recorded with Cs⁺-patch solution shown immediately after onset of whole-cell recording (A, trace 1). After 2 min, the drive potential is transformed into an inspiratory plateau response (2), which can also be evoked using 150 ms somatic current pulses (3). At 100 μm FFA reduces the endogenous (4) and evoked (5) responses. B, inspiratory plateaus evoked with 50 ms current steps were subjected to cumulative applications of 1 μm TTX, 200 μm Cd²⁺ and choline substitution for Na⁺ in the ACSF. Inset shows superimposition of the active responses immediately following current-pulse stimuli. C, inspiratory plateaus subjected to the same agents as in B (above), but with Cd²⁺ and choline substitution in reverse order. Inset is similarly constructed. D, inspiratory plateaus subjected to 1 μm TTX, and then cumulatively followed by 100 μm FFA and choline substitution. Inset is similarly constructed to B and C. Calibration bars in A apply to A–D and baseline membrane potential was −60 mV.