RAT PANCREATIC SECRETORY RESPONSE TO INTRADUODENAL INFUSION OF ELEMENTAL VS POLYMERIC DEFINED-FORMULA DIET

Pancreatic protein and fluid secretion in response to intraduodenal in fusion of polymeric and elemental liquid defined-formula diets were st udied in conscious rats. Rats were prepared with chronic pancreatic, b iliary, and duodenal cannulas and had their pancreatic secretions coll ected and continuously returned to the intestine during intraduodenal infusion with commercial liquid defined-formula diets. Ensure HN, a po lymeric defined formula diet containing intact protein, and two elemen tal diets, in which the protein component consisted of enzymatically h ydrolyzed protein and free amino acids, were tested. Ensure HN strongl y stimulated pancreatic protein and fluid secretion, causing a maximal 10-fold increase in protein secretion. In contrast, the elemental die ts stimulated only 30% to 47% of the protein secretion caused by Ensur e HN. Separate infusion of the fat, protein, and carbohydrate componen ts of one elemental diet, RTF Elemental, showed that fat was the major stimulant, but the responses to the separate components were not sign ificantly different from each other and none caused more than 50% of t he response to the complete diet. The results demonstrate that defined -formula elemental diets are much less stimulatory for pancreatic enzy me secretion than defined-formula polymeric diets in rats. The probabl e explanation for this difference is the replacement of intact protein by hydrolyzed protein and amino acids in the elemental diets.