Nutrient uptake by viscera drained by the portal vein in neonatal calves during intravenous infusion of glutamine

Objective-To quantify glutamine use by viscera drained by the portal vein i n neonatal calves and to determine whether uptake could be stimulated by lo ng-term IV infusion or long-term use of oral supplements. Animals-4 healthy neonatal calves. Procedure-A femoral artery, jugular vein, and the portal vein were surgical ly cannulated in each calf. Blood flow in the portal vein was measured, usi ng an ultrasonic transit-time flow probe. Calves were given an IV infusion of glutamine on days 6, 8, and 10 after surgery. Before the first infusion, calves were fed a diet of milk only. The diet was supplemented with glutam ine for the second and third infusions. Glutamine was administered via the jugular vein during a 5-hour period. Venous and arterial blood samples were collected every hour for 5 hours. Results-During glutamine infusion, uptake of glutamine by viscera drained b y the portal vein increased in association with increased production of amm onia. Glutamine supplementation of the diet did not alter glutamine uptake. Glutamine infusion did not increase viscera uptake of indispensable amino acids. Longterm use of glutamine supplements or infusion of glutamine for p eriods of more than 1 hour increased glutamine uptake by viscera. Arterial leucine concentration and uptake of leucine by the viscera decreased during glutamine infusion, indicating that leucine became the limiting factor. Conclusion-Glutamine administration (supplements or infusions) to calves ma y require that a mixture of amino acids be provided to improve effectivenes s. Clinical Relevance-Glutamine may be beneficial in treatments designed to pr omote intestinal healing in diarrheic calves.