Examination of metabolism of viscera drained by the portal vein in neonatal calves, using short-term intravenous infusions of glutamine and other nutrients

Abstract

Abstract Objective To quantify glutamine use in viscera drained by the portal vein in neonatal calves and to assess the relative nutritional importance of glutamine, glucose, and acetate for enterocytes. Animals 5 healthy neonatal calves. Procedure A femoral artery, jugular vein, and the portal vein were surgically cannulated in each calf. Blood flow in the portal vein was measured by use of an ultrasonographic transit-time flow probe. A series of solutions was infused on 4 days for each calf. On the infusion days, acetate, glucose, glutamine, and saline (0.9% NaCl; control) solutions were administered IV during 1-hour periods via the jugular vein. Venous and arterial blood samples were collected during the last 15 minutes of each 1-hour infusion. Results Uptake of glutamine and glucose by viscera drained by the portal vein was 0.3 ± 1.1 and 1.9 ± 3.1 µmol/kg0.75/min, respectively, during saline infusion. During acetate, glucose, and saline infusions, glucose was a greater source of energy for the intestines than was glutamine. However, during glutamine infusion, uptake of glutamine by viscera drained by the portal vein increased significantly (29.9 ± 11.2 µmol/kg0.75/min), which was associated with an increase in ammonia production (7.0 ± 0.5 µmol/kg0.75/min). Toxicosis was not associated with IV administration of glutamine. Conclusion Glutamine infusion resulted in an increase in glutamine uptake by viscera drained by the portal vein, which was associated with an increase in ammonia production and a slight increase in oxygen consumption. Clinical Relevance These solutions may be used to develop treatments that enhance healing of intestines of diarrheic calves. (Am J Vet Res 1999;60:437-445)