EFFECT OF INTRAVENOUS GLUCOSE-INFUSION ON METABOLISM OF PORTAL-DRAINED VISCERA IN SHEEP FED A CEREAL STRAW-BASED DIET

This experiment investigated the effect of intrajugular infusion of gl ucose on whole-body glucose metabolism and the absorption of nutrients by the portal-drained viscera of four Suffolks-cross sheep, average B W 46 +/- 7 kg, fed a cereal/straw-based pelleted diet. Each sheep rece ived by random allocation 0 (control), 1.0, or 2.0 mg of glucose kg BW -1. min(-1) for 8 h infused into the jugular vein. Glucose irreversibl e loss rate, measured by simultaneous infusion of 6-[H-3]-glucose, inc reased approximately stoichiometrically during glucose infusion (.51, .75, and 1.09 error mean square [EMS].032 mmol/min for control, 1.0, a nd 2.0 mg of glucose infused . kg BW-1. min(-1), respectively). Utiliz ation of glucose increased in portal tissues (P=.089) as a result of g lucose infusion (.17,.18, and .33 EMS .008 mmol/ min) and was a consta nt proportion of glucose irreversible loss (.28). Portal blood flow wa s not affected by glucose infusion (overall mean 1.13L/min EMS.034). N et portal absorption of acetate increased during glucose infusion alth ough ruminal VFA concentrations were not affected. In contrast, net fr ee amino acid absorption by portal-drained tissues was reduced during glucose infusion (291, 115, and 4 EMS 33,816 mu mol/min, P=.054). Thes e results show that metabolism of nutrients across the gut wall is inf luenced by glucose availability to gastrointestinal tissues and affect s the pattern of nutrients available to the liver and peripheral tissu es.