title: Alterations in enterkinase, trypsin, and alkaline phosphatase in response to variation in dietary protein content in the rat.
abstract: In rats fed equal amounts of isocaloric high-protein (HPR) and low-protein (LPR) diets, studies were performed on the mucosal activities of enterokinase and alkaline phosphatase and on the activities of these enzymes and of trypsin in washings obtained from the contents of two standard 5 cm. segments of duodenum, located proximal (Segment I) and distal (Segment II) to the main pancreatic duct. Mean mucosal weights and tissue protein per segment were 1.3-fold higher in rats fed HPR diets. In Segment I, but not Segment II, mucosal activities per segment were higher in HPR for enterkinase (threefold) and alkaline phosphatase (twofold). In luminal washings trypsin did not differ between the two groups; in HPR luminal levels of enterkinase were significantly higher in Segment II and those of alkaline phosphatase were similarly elevated in Segment I. Irrespective of diet the major activity of both enzymes was in mucosal fractions. Studies of total activity of each enzyme showed that the enzymes behave rather similarly, with the major differences between the dietary groups discernible in Segment I. These data stress the importance of dietary protein content in intestinal enzyme adaptation and reveal regional variation in the responses of the different enzymes.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D004044:Dietary Proteins; D004386:Duodenum / Q000201:enzymology*; D010450:Endopeptidases / Q000378:metabolism*; D004765:Enteropeptidase / Q000378:metabolism*; D009092:Mucous Membrane / Q000201:enzymology; D051381:Rats; D014357:Trypsin / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D000469:Alkaline Phosphatase; D010450:Endopeptidases; D014357:Trypsin; D004765:Enteropeptidase