Calcium Influx through Channels Other than Voltage-Dependent Calcium Channels Is Critical to the Pituitary Adenylate Cyclase-Activating Polypeptide-Induced Increase in Excitability in Guinea Pig Cardiac Neurons

: Pituitary adenylate cyclase‐activating polypeptide (PACAP) effects on intracellular calcium ([Ca2+]i) and excitability have been studied in adult guinea pig intracardiac neurons. PACAP increased excitability, but did not elicit Ca2+ release from intracellular stores. Exposure to a Ca2+‐deficient solution did not deplete [Ca2+]i stores but did eliminate the PACAP‐induced increase in excitability. We postulate that Ca2+ influx is required for the PACAP‐induced increase in excitability.