Exit routes for secretory proteins from the dog pancreas

The relative importance of the pancreatic venous and lymphatic routes for the transport of enzymes away from the pancreas was investigated. The activities of lipase and amylase were compared in arterial plasma, pancreaticoduodenal lymph and venous plasma, pancreatic interstitial fluid and juice in 31 anaesthetized dogs. Enzyme activities were determined before, during and after stimulation of the acinar parenchyma by 4 U/kg b.w. secretin + CCK-PZ for 60 min. During stimulation either is the juice secreted into the duodenum or we ligated the main pancreatic duct. Enzyme output was calculated as the volume x enzyme activity. Initial activities of both enzymes were higher in lymph than in plasma samples. Pancreatic stimulation raised the level of both enzymes in plasma. Stimulation raised lymph lipase activity higher than in plasma, even without duct ligation. Duct ligation increased enzyme activities to considerably higher values in oedema fluid than in lymph. When enzyme output in the stimulated juice for 60 min was considered 100%, output in plasma volume (5% of b.w.) was about 15% both for lipase and for amylase during stimulated secretion, 25--30% for both enzymes when duct had been ligated. Lymphatic enzyme output was found negligible.

during pancreatic stimulation biologically important amounts of secretory proteins enter the blood circulation. The lymphatic transport is negligible, since pancreatic lymph flow is several hundred times less than blood flow.