Histamine release induced by pituitary adenylate cyclase activating polypeptide from rat peritoneal mast cells

Pituitary Adenylate Cyclase activating polypeptide 38 (PACAP 38) and its fragments PACAP 27, PACAP 16-38, PACAP 28-38, PACAP 31-38 were compared for their histamine releasing effects on rat peritoneal mast cells. PACAP 38 and PACAP 16-38 were the most active peptides, followed by PACAP 27. PACAP 38 and PACAP 16-38 dose-dependently increased histamine release at a concentration of 1 x 10(-8) mol/l or higher, and these releasing activities were more than 100 times more potent than that of substance P. Extracellular calcium inhibited the substance P-induced histamine release. In contrast, PACAP 38- and PACAP 27-induced histamine releases were hardly inhibited by extracellular calcium.