Effect of motilin on pancreatic secretion

Motilin and secretin were compared in regard to their effects on pancreatic bicarbonate and protein secretion in conscious dogs provided with chronic pancreatic fistulas. Dose-response analysis showed that maximal bicarbonate response to motilin was about 5% of that to secretin and maximal protein response was about 35% of that to caerulein. The interaction of these two peptides showed that motilin is a potent inhibitor of secretin-induced bicarbonate secretion. Since motilin is released by duodenal alkalinization and inhibits pancreatic bicarbonate secretion, it is possible that this peptide is involved in the feedback mechanism of inhibition of pancreatic secretion by alkaline pancreatic juice present in the duodenum.