Pituitary adenylate cyclase-activating polypeptide: a potent activator of human intestinal ion transport.

To investigate the effects of PACAP-27 on electrolyte transport across the isolated human intestinal mucosa, changes in short-circuit current (Isc) were measured in Ussing chamber experiments. Serosally added PACAP-27 increased Isc in a concentration-dependent manner, eliciting a similar maximal effect in both the jejunal and the colonic mucosa. Bumetanide inhibited Isc responses, indicating stimulation of Cl- secretion. The potency and efficacy of PACAP-27 were comparable to those of VIP, suggesting that both peptides activate intestinal secretion by way of a common receptor located in the basolateral membrane of the intestinal epithelium.