Discharge of newly synthesized proteins in pure juice collected from the human pancreas. Indication of more than one pool of intracellular digestive enzymes.

The pancreatic secretion of 6 normal human volunteers was collected by endoscopic cannulation of the main pancreatic duct. The appearance of newly synthesized proteins was monitored at 1-min intervals after labeling with [75Se]methionine. The minimum transit time of these proteins from their site of synthesis to the acinar lumen was 36 +/- 8 min. Stimulation of protein secretion by a rapid intravenous injection of caerulein (40 ng per kg), 1 hr after [75Se]methionine administration, greatly decreased (by 73% on an average) the specific radioactivity of the discharged proteins. These data support the concept of a functional heterogeneity of proteins secreted by the human pancreas.