INTRAUTERINE GROWTH RESTRICTION DOES NOT ALTER RESPONSE OF PROTEIN-SYNTHESIS TO FEEDING IN NEWBORN PIGS

This study aimed to determine the effect of intrauterine growth restri ction (IUGR) on the acute response of tissue protein synthesis to feed ing in newborn pigs. Newborn pigs of sows fed either control or protei n-restricted diets throughout gestation were designated C or IUGR, res pectively Both groups were either fasted for 9 h after birth or fed ho urly 30 ml colostrum/kg body wt for 2.75 h after a 6-h fast. Fractiona l rates of tissue protein synthesis (K-s) were measured in vivo with a flooding dose of L-[4-H-3]phenylalanine. Birth weight was reduced by 33% in IUGR pigs. IUGR had no effect on K-s in skeletal muscles, heart , liver, jejunum, or pancreas. Feeding stimulated tissue K-s similarly in C and IUGR pigs. Fasting plasma insulin concentrations and their r ise with feeding were unaffected by IUGR. Plasma insulin-like growth f actor I(IGF-I) concentrations were reduced by 42% in IUGR pigs and wer e not altered by feeding in either IUGR or C pigs. There were positive nonlinear relationships between tissue Ks and circulating concentrati ons of insulin. The results indicate that, in newborn pigs, tissue K-s are unaffected by IUGR, despite reduced plasma IGF-I concentrations. The efficiency with which nutrients stimulate tissue K-s is also not a ltered by IUGR, perhaps because the rise in plasma insulin concentrati ons with feeding is unaffected by IUGR.