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

Objective-To quantify glutamine use in viscera drained by the portal vein i n neonatal calves and to assess the relative nutritional importance of glut amine, glucose, and acetate for enterocytes. Animals-5 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 by u se of an ultrasonographic transit-lime flow probe. A series of solutions wa s infused on 4 days for each calf. On the infusion days, acetate, glucose, glutamine, and saline (0.9% NaCl; control) solutions were administered IV d uring 1-hour periods via the jugular vein. Venous and arterial blood sample s were collected during the last 15 minutes of each 1-hour infusion. Results-Uptake of glutamine and glucose by viscera drained by the portal ve in was 0.3 +/- 1.1 and 1.9 +/- 3.1 mu mol/kg(0.75)/min, respectively, durin g saline infusion. During acetate, glucose, and saline infusions, glucose w as a greater source of energy for the intestines than was glutamine. Howeve r, during glutamine infusion, uptake of glutamine by viscera drained by the portal vein increased significantly (29.9 +/- 11.2 mu mol/kg(0.75)/min), w hich was associated with an increase in ammonia production (7.0 +/- 0.5 mu mol/kg(0.75)/min). Toxicosis was not associated with IV administration of g lutamine. Conclusion-Glutamine infusion resulted in an increase in glutamine uptake b y 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 e nhance healing of intestines of diarrheic calves.