title: Pancreatic digestive enzyme secretion in the rabbit: rapid cyclic variations in enzyme composition.
abstract: The role and mechanism of nonparallel pancreatic secretion of digestive enzymes, in which enzyme proportions change in rapidly regulated fashion, remain controversial. Secretion was collected from male 2.2-kg New Zealand rabbits in 5-min intervals for 3 h under basal conditions or constant stimulation with cholecystokinin (CCK; 0.1 microgram per kg per h i.v.) or methacholine chloride (MCh; 40 micrograms per kg per h i.v.). Both CCK and MCh produced an 8-fold stimulation of protein output. Enzymes were separated by SDS/PAGE and quantitated by densitometry of Coomassie blue-stained gels. Under both basal conditions and constant MCh infusion, rapid neurosecretory-like 12-min cyclic changes occurred in the proportions of amylase, lipase I, chymotrypsinogen, and trypsinogen. During constant infusion their percentages changed as much as 10-fold, and their ratios cycled by as much as 30-fold. The mean percentage for the entire infusion period for lipase I declined > 25% with CCK or MCh, for amylase it rose approximately 30%, and for chymotrypsinogen and trypsinogen it doubled (for all, P < 0.05). CCK and MCh elicited subtly but significantly different mean enzyme percentages and enzyme ratios (P < 0.05) for amylase, chymotrypsinogen, and trypsinogen; these differences were also confirmed by regression and correlation analyses. The changes in enzyme percentages and ratios were explicitly consistent with secretagogue-caused shifts in the intrapancreatic enzyme secretory sources. Nonparallel secretion of digestive enzymes occurs routinely, even during constant stimulation, and is due to cyclic neurosecretory-like secretion from heterogeneous intrapancreatic sources.
authors.affiliation: Department of Pediatrics, Rhode Island Hospital, Brown University School of Medicine, Providence 02903, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Adelson
authors.forename: R
authors.initials: R
authors.lastname: Clarizio
authors.forename: J A
authors.initials: JA
authors.lastname: Coutu
mesh_terms: D000204:Activity Cycles; D000681:Amylases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology; D002919:Chymotrypsinogen / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008049:Lipase / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology; D010189:Pancreatic Juice / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D011817:Rabbits; D012044:Regression Analysis; D014362:Trypsinogen / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D016210:Methacholine Chloride; D014362:Trypsinogen; D002766:Cholecystokinin; D002919:Chymotrypsinogen; D008049:Lipase; D000681:Amylases