Figure 7. Superfusion of sodium butyrate increased reversibly the cellular excitability of mucosally projecting myenteric AH neurones.

Superfusion with 1 mM sodium butyrate (time of superfusion indicated by the bar) increased the number of action potential discharges (large amplitude deflections) in response to depolarizing current pulses of 0.04 nA (current trace of depolarizing pulses of 300 ms duration given at 0.3 Hz not shown). Before perfusion of butyrate every 7th or 8th depolarizing pulse led to action potential discharge; in butyrate every 3rd or 4th depolarizing pulse led to action potential discharge. Note also the decrease in duration of the late after-hyperpolarization during butyrate superfusion. After wash-out the excitability level of the neurone returned to pre-butyrate levels.