Circadian pancreatic enzyme pattern and relationship between secretory and motor activity in fasting humans

It is unknown whether nonparallel pancreatic enzyme output occurs under basal conditions in humans. We aimed to determine whether the circadian or wake-sleep cycle influences the relationship among pancreatic enzymes or between pancreatic secretory and jejunal motor activity. Using orojejunal multilumen intubation, we measured enzyme outputs and proximal jejunal motility index during consecutive daytime and nighttime periods in each of seven fasting, healthy volunteers. Enzyme outputs were correlated tightly during daytime phases of wakefulness and nighttime phases of sleep (r > 0.72, P < 0.001). During nocturnal phases of wakefulness, output of proteases (r = 0.84, P < 0.001), but not of amylase and trypsin (r = 0.12), remained associated. Nocturnally, particularly during sleep, pancreatic secretory activity was directly correlated with jejunal motility index (r > 0.50, P < 0.001). In conclusion, parallel secretion of pancreatic enzymes dominates throughout the circadian cycle. Nonparallel secretion during nocturnal phases of wakefulness may be due to merely circadian effects or to the coupling of the wake-sleep and the circadian cycle. The association between fluctuations of secretory and motor activity appears to be particularly tight during the night.