Fig. 9.

The PACAP-induced increase in cardiac neuron membrane excitability is concentration dependent. A, The number of action potentials elicited by 500 msec depolarizing current pulses of increasing intensity (0.1–0.5 nA) was augmented with increasing concentrations of superfused PACAP27 (0.1–100 nm peptide). B, The concentration dependence of increased membrane excitability in response to PACAP27 or PACAP38 superfusion was examined by determining the number of action potentials produced by increasing stimulus intensities (0.1–0.5 nA; 500 msec duration).