抄録
The stimulation of pancreatic enzymesecretion by diet components was investigated with a pancreatic duct cannula in rats. The infusion of casein into the duodenumresulted in a marked stimulation of the enzymesecretion. Onthe contrary, an aminoacid mixture simulated casein composition had no effect. Someoligopeptides, starch, sucrose, glucose, soybean oil and other commondiet componentsalso did not stimulate pancreatic enzymesecretion. A dose-response relationship was observed between the protein infusion level and the stimulation intensity of pancreatic enzyme secretion. Synthetic substrates for trypsin, tosyl-arginine methyl ester and benzoyl-arginine-p-nitroanilide, and for chymotrypsin, benzoyl-tyrosine ethyl ester, stimulated the enzyme secretion as well as casein; however, a typical substrate for aminopeptidase, leucine-p- nitroanilide, had no effect. These findings suggest that the substrates for pancreatic proteases can act primarily as secretagogues amongmanydiet components.
The ability as a secretagogue was more potent in casein than a-lactalbumin. Native ovalbumin was hardly digested by pancreatin in vitro. However, mild heat-denaturation of this protein considerably improved both its digestibility and ability as a secretagogue. It can be explained that mild heat-denaturation of the protein improves its availability as a substrate for pancreatic protease.
Based on these results, a mechanismby which substrate protein is recognized for pancreatic enzymesecretion in the rat intestine is discussed.
