A, mean magnitude of IH at -110 mV for neurons with only tetrodotoxin-sensitive sodium currents (TTX-S) or for neurons with both tetrodotoxin-sensitive and -resistant sodium currents (TTX-R). *P < 0.001; n is given in parentheses. B, amplitude of IH at -110 mV was plotted with respect to the capacitance of the neuron. Neurons with only tetrodotoxin-sensitive sodium currents (•, n= 13), with tetrodotoxin-sensitive and -resistant sodium currents (^, n= 43; ▵, n= 5) or with capsaicin-sensitive channels (▵, n= 5) are illustrated.