The induction of citrulline synthesis from glutamine in enterocytes of weaned pigs is not due primarily to age or change in diet.
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This study was designed to determine the roles of age and diet in the induction of citrulline synthesis from glutamine in enterocytes of weaned pigs. Enterocytes were prepared from the jejunum of suckling pigs (14-29 d old), 23- and 29-d-old pigs weaned at 21 d of age to either a conventional corn-soybean meal-based or a milk-based diet, and 23-d-old pigs weaned at 21 d of age and food-deprived for 2 d. Cells were incubated at 37 degrees C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) in the presence of 5 mmol/L glucose with or without 2 mmol/L glutamine. The rate of citrulline production from glutamine was similar in enterocytes from 14-, 21- and 29-d-old suckling pigs, and was 10-fold greater in cells from 29-d-old weaned pigs. After weaning, enterocytes from 23-d-old pigs fed the milk-based diet had a 33% higher rate of citrulline production from glutamine than cells from age-matched pigs fed a corn-soybean meal-based diet or food-deprived for 2 d. Our findings suggest that the major determinant of the induction of citrulline synthesis from glutamine in enterocytes of weaned pigs may not be age or change in diet, although the extent of the induction may be slightly influenced by diet composition.