title: Circadian and ultradian variation in pancreatic secretion of meal-fed pigs after weaning.
abstract: We studied the time structure of pancreatic secretion in two experiments involving seven 6- to 7-wk-old intact male pigs, surgically fitted with a jugular vein catheter for blood sampling, pancreatic catheter, and a duodenal T-cannula for chronic pancreatic juice sampling for 72 h at 30- to 60-min intervals. Pigs were kept in metabolic cages in a regimen of 12 h of light alternating with 12 h of darkness and were fed at 0800, 1500, and 2200 daily a standard diet based on barley, soybean meal, and fish meal. Beginning 4 d after surgical recovery, three 24-h collections of pancreatic juice and blood sampling were begun either at 0700 or 0800 every 2nd d for 5 d. Pancreatic secretion exhibited a pattern characterized by distinct meal-related secretions of the first phase (postprandial), containing large amounts of protein and enzymes (trypsin and chymotrypsin), and by non-food-stimulated secretions of the second phase with less protein and enzymes. During the dark span, the first phase was practically absent; the response of the pancreatic secretion to the 2200 meal was not very pronounced. Apart from the anticipated circadian rhythm demonstrable by single cosinor analysis on a group basis, a prominent 8-h component was almost invariably statistically significant. Moreover, an approximately 3.43-h component was also prominent. These data indicate that pancreatic secretions are circadian periodic and that their response to a standard meal is also circadian-stage dependent. The circadian components may have been free-running because the pigs were adjusting themselves to the changing phase and that resulted in the period being different from exactly 24 h.
authors.affiliation: Department of Animal Physiology, University of Lund, Sweden.
authors.forename: M J
authors.initials: MJ
authors.lastname: Thaela
authors.forename: M S
authors.initials: MS
authors.lastname: Jensen
authors.forename: G
authors.initials: G
authors.lastname: Cornélissen
authors.forename: F
authors.initials: F
authors.lastname: Halberg
authors.forename: F
authors.initials: F
authors.lastname: Nöddegaard
authors.forename: K
authors.initials: K
authors.lastname: Jakobsen
authors.forename: S G
authors.initials: SG
authors.lastname: Pierzynowski
mesh_terms: D000204:Activity Cycles / Q000502:physiology*; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D008297:Male; D010189:Pancreatic Juice / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D019518:Postprandial Period / Q000502:physiology*; D011506:Proteins / Q000032:analysis / Q000378:metabolism; D013552:Swine / Q000502:physiology*; D013997:Time Factors; D014357:Trypsin / Q000032:analysis / Q000378:metabolism; D014886:Weaning
chemical_list: D011506:Proteins; D014357:Trypsin