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

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.