Figure 4. Effect of addition of TTX to the perfusate on nerve activity in normoxia and hypoxia.
A, perfusate PO2 and nerve activity before, during and following a 2 min perfusion with saline containing 25 nM TTX (bar). Inset, oscillographic tracing of recorded action potential triggered by the unit pulse. Sweep length was 10 ms. B, same as A but perfusate was moderately hypoxic. C, ratio of nerve activities (means ±s.e.m.) measured following addition of TTX and before addition of TTX (control). TTX caused a significant reduction in discharge frequency during normoxia (P < 0.05, n = 6) and during hypoxia (P < 0.01, n = 6).