Effect of low dose secretin and caerulein on pure pancreatic bicarbonate secretion and plasma secretin in man.

In six healthy volunteers pure pancreatic juice was obtained by endoscopic cannulation of the main pancreatic duct. Following a 20-min basal period, secretin (0.03 CU/kg, h) was intravenously infused alone for 20 min and then with caerulein 15 ng/kg, h for further 20 min. From a basal level of 28 +/- 13 mu mol/5 min, secretin by itself significantly increased pancreatic bicarbonate to 182 +/- 24 mu mol/5 min. A further significant two-fold increase to 396 +/- 50 mu mol/5 min was observed during caerulein. The increment in plasma secretin of 2.1 +/- 0.3 pmol/l is comparable to the rise that may be observed post-prandially. It is concluded that secretin in combination with cholecystokinin may indeed play a physiological role in the regulation of duodenal pH.