Permeability of adolescent rat intestine to pancreatic ribonuclease

There are indications that exocrine pancreatic enzymes may undergo an enteric recirculation. Ribonuclease (RNase) is present in considerable quantities in pancreatic exocrine secretions. Therefore we studied the intestinal transport of pancreatic RNase using everted gut sacs from duodenum, midgut, and ileum of young rats. Gut sacs were incubated aerobically at 37 degrees C, 22 degrees C, and 0 degrees C, and anaerobically at 37 degrees C. Measurable amounts of RNase crossed the intestinal barrier, but neither duodenum, midgut nor ileum absorbed RNase preferentially. The experimental data favor simple diffusion of RNase across rat small bowel. However, the amounts of pancreatic RNase absorbed were small. Thus, while our data do not negate the concept of an enteropancreatic recirculation in the rat, only a minor quantity of luminal, pancreatic RNase could recirculate.