Effect of secretin and caerulein on pancreatic polypeptide and on insulin secretion from the isolated perfused ventral area of the rat pancreas.

The secretion of pancreatic polypeptide (PP) and insulin (IRI), stimulated by secretin or caerulein was investigated in the isolated perfused ventral area of the rat pancreas. The effect of atropine on these secretory responses was examined. Secretin (100-1000 pM) stimulated transient PP secretion and this response was completely inhibited by 10 microM of atropine. However, 10 pM secretin and 10-1000 pM caerulein did not stimulate the secretion of PP. Caerulein transiently stimulated IRI secretion and this response was not inhibited by atropine, but 10-1000 pM secretin did not stimulate IRI secretion. Therefore, the supraphysiological dose of secretin stimulates PP secretion probably via an intrapancreatic release of acetylcholine, while caerulein stimulates IRI secretion by a direct action.