title: Quantitative role of splanchnic region in leucine metabolism: L-[1-13C,15N]leucine and substrate balance studies.
abstract: The role of the splanchnic region (Sp) in whole body leucine metabolism was assessed in six chronically catheterized fasting mongrel dogs and in eight dogs during constant enteral feeding of a complete amino acid solution (0.24 g.kg-1.h-1). We used primed continuous intravenous infusions of L-[1-13C,15N]leucine and L-[1-14C]leucine and measurements of arteriovenous isotope and leucine balance across the gut, liver, and Sp. In the fasted condition, 3.5% of arterial leucine supply was oxidized in the Sp, accounting for 13% of total body leucine oxidation, with 10% by liver. With amino acid feeding 1) leucine carbon and nitrogen fluxes and oxidation were increased (P less than 0.01) at the whole body level; 2) the percent of whole body leucine oxidation occurring in the Sp and liver increased (P less than 0.01) to 41 and 27%, respectively; 3) fractional metabolic utilization of leucine delivered to the Sp was reduced (P less than 0.01) from 47 to 35%; 4) the deamination rate of leucine in the gut was increased (P less than 0.05), along with an increased reamination rate of alpha-ketoisocaproic acid in the Sp (P less than 0.05). These findings reveal that the Sp accounts for a small fraction of whole body leucine oxidation during the fasting condition, but it plays a quantitatively important role in total body leucine oxidation during amino acid feeding; the gut and liver play cooperative roles in controlling leucine supply to peripheral tissues.
authors.affiliation: Shriners Burns Institute, Massachusetts.
authors.forename: Y M
authors.initials: YM
authors.lastname: Yu
authors.forename: D A
authors.initials: DA
authors.lastname: Wagner
authors.forename: E E
authors.initials: EE
authors.lastname: Tredget
authors.forename: J A
authors.initials: JA
authors.lastname: Walaszewski
authors.forename: J F
authors.initials: JF
authors.lastname: Burke
authors.forename: V R
authors.initials: VR
authors.lastname: Young
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D004285:Dogs; D005260:Female; D007408:Intestinal Absorption; D007422:Intestines / Q000098:blood supply / Q000502:physiology; D007553:Isotope Labeling; D007930:Leucine / Q000378:metabolism*; D008099:Liver / Q000502:physiology; D008102:Liver Circulation; D008297:Male; D008433:Mathematics; D008954:Models, Biological; D009587:Nitrogen Isotopes; D012039:Regional Blood Flow; D013152:Splanchnic Circulation / Q000502:physiology*
chemical_list: D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D009587:Nitrogen Isotopes; D007930:Leucine