The objective of this study was to determine whether bombesin can stimulate pancreatic exocrine secretion and release of cholecystokinin-33 and gastrin in pigs. Bombesin (1 microgram/kg-hr) was infused intravenously in six conscious piglets for one hour, and pancreatic secretions, plasma, and serum were collected. Cholecystokinin-33 and gastrin were measured by specific radioimmunoassays. Pancreatic secretory volume increased from a basal value of 1.5 +/- 0.5 mL/15 min to 10.4 +/- 1.7 mL/15 min. Pancreatic protein output increased from basal values of 7.9 +/- 2.4 mg/15 min to 88.9 +/- 25.4 mg/15 min. Plasma cholecystokinin-33 increased significantly from a basal concentration of 130 +/- 40 pg/mL to 275 +/- 100 pg/mL, as did gastrin (40.7 pg/mL to 200 +/- 27 pg/mL). Our findings demonstrated that bombesin stimulates exocrine pancreatic secretion in pigs; we conclude that this stimulation is due largely to the release of cholecystokinin.