Diurnal profile of pancreatic exocrine secretion and plasma levels of gut hormones (cholecystokinin and pancreatic polypeptide).

We examined diurnal changes of pancreatic exocrine secretion and plasma levels of cholecystokinin (CCK) and human pancreatic polypeptide (hPP) in men with postoperative transient external pancreatic drainage (3 with pancreatico-jejunostomy: PJ, and 5 with pancreato-duodenectomy:PD). Plasma CCK levels increased and the pancreatic exocrine secretion showed a corresponding increase after meals in both groups. In the PJ group hPP levels increased after meals and there was a significant correlation between the plasma levels of CCK and hPP. In the PD group the plasma hPP levels were not detectable throughout the study and there was a better correlation between the exocrine secretion and the plasma CCK levels than in the PJ group. Plasma CCK levels showed rhythmic changes associated with pancreatic exocrine secretion, with no significant changes in plasma glucose and insulin in the night (24:00-07:00). These results suggested that (1) the resection of the pancreatic head which is rich in hPP contents led to a complete loss of anti-CCK effects on CCK, and that (2) fluctuation in plasma CCK levels, in the fasting state, might initiate pancreatic exocrine secretion.