Effect of dopamine on pancreatic secretion in the dog.

1. Effects of L-dopa and dopamine on the secretion of pancreatic juice were investigated in preparations of the isolated blood-perfused canine pancreas.2. Dopamine (1-10 mug) given intra-arterially caused a profuse flow of juice.3. The secretory activity of dopamine (3 mug) was approximately equal to that of secretin (0.1 unit).4. L-Dopa (10-100 mug) given by a single intra-arterial injection was ineffective, but infusion at 100 mug/min for 10 min caused a marked increase of secretion after a delay of a few minutes.5. Intravenous administration of either L-dopa (3 mg/kg) or dopamine (10-100 mug/kg) elicited a marked increase of pancreatic secretion, but was definitely less effective than intra-arterial injection.6. Dopamine-induced secretion was not modified by atropine, phentolamine, propranolol, guanethidine or tetrodotoxin.7. It is concluded that dopamine acts directly on the exocrine cells in the pancreas.