Intestinal lysine metabolism is driven by the enteral availability of dietary lysine in piglets fed a bolus meal

Am J Physiol Endocrinol Metab. 2003 Dec;285(6):E1246-57. doi: 10.1152/ajpendo.00150.2003. Epub 2003 Jul 8.


Previous steady-state continuous-feeding studies have shown that the gut mucosa removes substantial amounts of both dietary and systemic amino acids. However, enteral nutrition is often given under non-steady-state conditions as a bolus meal, and this has been shown to influence systemic metabolism. Therefore, our aim was to quantify the relative metabolism of dietary and systemic lysine by the portal-drained viscera (PDV) under non-steady-state conditions after a single bolus meal. Five 28-day-old piglets implanted with arterial, venous, and portal catheters and with an ultrasonic portal flow probe were given an oral bolus feeding of a milk formula containing a trace quantity of intrinsically 15N-labeled soy protein and a continuous intravenous infusion of [U-13C]lysine for 8 h. Total lysine use by the PDV was maximal 1 h after the meal (891 micromol x kg(-1) x h(-1)) and was predominantly of dietary origin (89%), paralleling the enteral delivery of dietary lysine. Intestinal lysine use returned to a low level after 4 h postprandially and was derived exclusively from the arterial supply until 8 h. Cumulative systemic appearance of dietary lysine reached 44 and 80% of the ingested amount 4 and 8 h after the meal, respectively, whereas the PDV first-pass use of dietary lysine was 55 and 32% of the intake for these two periods, respectively. We conclude that the first-pass utilization rate of dietary lysine by the PDV is directly increased by the enteral lysine availability and that it is higher with a bolus than with continuous oral feeding.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptation, Physiological
  • Amino Acids, Essential / administration & dosage*
  • Amino Acids, Essential / blood
  • Amino Acids, Essential / metabolism*
  • Amino Acids, Essential / pharmacokinetics
  • Animals
  • Biological Availability
  • Blood Glucose / analysis*
  • Diet / methods
  • Digestive System / blood supply
  • Digestive System / metabolism*
  • Female
  • Food, Fortified
  • Hepatic Artery / metabolism
  • Intestinal Mucosa / metabolism
  • Intestines / blood supply
  • Lysine / administration & dosage*
  • Lysine / blood
  • Lysine / metabolism*
  • Lysine / pharmacokinetics
  • Metabolic Clearance Rate
  • Nutritional Physiological Phenomena
  • Portal Vein / metabolism*
  • Postprandial Period / physiology
  • Swine


  • Amino Acids, Essential
  • Blood Glucose
  • Lysine