GROWTH AND METABOLISM OF GASTROINTESTINAL AND SKELETAL-MUSCLE TISSUESIN PROTEIN-MALNOURISHED NEONATAL PIGS

Our objective was to, determine whether neonates adapt to protein maln utrition by preserving the relative growth and metabolism of gastroint estinal tissue at the expense of skeletal muscle. We measured gastroin testinal, liver, and carcass tissue masses and blood flow, oxygen cons umption, and net glucose and amino acid fluxes in vivo of the portal-d rained visceral tissues (PDV) in neonatal pigs fed isocaloric diets co ntaining either 30% protein [control (C)] or 15% [low protein (LP)] fo r 14 days. Relative protein mass and fasting blood flow and oxygen con sumption of PDV tissue in either group were not different. Relative pr otein mass; of liver and carcass was lower in LP pigs. Net essential a mino acid absorption; and insulin concentration after feeding were low er in LP pigs. Results demonstrate that protein malnutrition in neonat al pigs differentially altered rates of tissue growth, such that the p roportion of body protein partitioned into gastrointestinal tissue was preserved, while that of skeletal muscle was reduced. Chronic reducti on in amino acid absorption in protein-malnourished pigs resulted in a reduced insulin response to feeding, which presumably limited substra te availability and the anabolic stimulus for skeletal muscle protein accretion.