Secretory characteristics of pancreatic γ-glutamyl transpeptidase

Summary

In an attempt to identify the secretory mechanism of pancreatic γ-glutamyl transpeptidase (γ-GTP), constant intravenous infusions of secretin alone and in combination with caerulein were performed in anesthetized dogs prepared with a pancreatic fistula. Caerulein produced a marked increase in amylase concentration and only a slight increase in γ-GTP. γ-GTP concentration of the pancreatic juice varied from 12 to 490 mU per ml which ranged up to 188-fold higher than that of the serum. The enzyme concentration depended largely on the flow rate, revealing 3 characteristic curvlinear relationship, regardless of whether caerulein was added to the secretin infusion. No significant relation was demonstrated between amylase concentration and flow rate, amylase and γ-GTP concentrations, and γ-GTP and protein concentration. An inverse linear correlation between γ-GTP and chloride concentrations was obtained when flow rate was below 2.5 ml per 15 min. A significant linear relationship was demonstrated between γ-GTP and leucine aminopeptidase concentrations, and amylase and protein concentrations. The results presented clearly demonstrate that the mechanism of pancreatic secretion of γ-GTP is quite distinct from that of amylase.