Adelson J W, Clarizio R, Coutu J A
Department of Pediatrics, Rhode Island Hospital, Brown University School of Medicine, Providence 02903, USA.
Proc Natl Acad Sci U S A. 1995 Mar 28;92(7):2553-7. doi: 10.1073/pnas.92.7.2553.
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.
消化酶非平行胰腺分泌的作用和机制仍存在争议，在这种分泌过程中，酶的比例以快速调节的方式变化。在基础条件下或用胆囊收缩素（CCK；每千克每小时静脉注射0.1微克）或氯化乙酰甲胆碱（MCh；每千克每小时静脉注射40微克）持续刺激下，以5分钟的间隔从体重2.2千克的雄性新西兰兔收集3小时的分泌物。CCK和MCh均使蛋白质分泌增加了8倍。通过SDS/PAGE分离酶，并通过考马斯亮蓝染色凝胶的光密度测定法定量。在基础条件和持续输注MCh的情况下，淀粉酶、脂肪酶I、胰凝乳蛋白酶原和胰蛋白酶原的比例均出现类似神经分泌的12分钟周期性快速变化。在持续输注期间，它们的百分比变化高达10倍，其比例循环变化高达30倍。在整个输注期间，脂肪酶I的平均百分比在CCK或MCh作用下下降超过25%，淀粉酶上升约30%，胰凝乳蛋白酶原和胰蛋白酶原翻倍（所有情况，P<0.05）。CCK和MCh引起的淀粉酶、胰凝乳蛋白酶原和胰蛋白酶原的平均酶百分比和酶比例存在细微但显著的差异（P<0.05）；回归和相关分析也证实了这些差异。酶百分比和比例的变化与促分泌剂引起的胰腺内酶分泌源的转移明显一致。即使在持续刺激期间，消化酶的非平行分泌也经常发生，这是由于胰腺内异质来源的类似神经分泌的周期性分泌所致。
