Fig. 5.

Differential effects of iberiotoxin (IbTX) on neuronal excitability using an intact vagal ganglion preparation. With the use of CV as a definitive measure of afferent type, somatic action potentials were elicited by brief current stimulation through the patch electrode. Application of 100 nM of IbTX had no effect on myelinated A-type VGN (A), while in contrast action potentials from unmyelinated C-type VGN (B) broadened much in the same manner as with application of 100 nM ChTX. In response to step depolarizing currents, the repetitive discharge characteristics of myelinated A-type afferents (C) were unchanged, while unmyelinated C-type afferents (D) were markedly more excitable in the presence of 100 nM IbTX (gray traces). See Table 1 for summary data.