Item – Theses Canada

OCLC number
577899023
Link(s) to full text
LAC copy
LAC copy
Author
Urschel, Kristine Laura,1980-
Title
Arginine synthesis and metabolism in neonatal piglets.
Degree
Ph. D. -- University of Alberta, 2007
Publisher
Ottawa : Library and Archives Canada = Bibliothèque et Archives Canada, [2008]
Description
4 microfiches
Notes
Includes bibliographical references.
Abstract
Arginine is an indispensable amino acid for neonates, because although they can synthesize some arginine, it is not enough to maintain health or support optimum growth. The main objective of this thesis was to study the sites and limitations of arginine synthesis in neonatal piglets. Five studies were conducted using a multi-catheterized piglet model, which allowed for tight control of dietary intake (either enteral or parenteral), isotope infusion and blood sampling. Stable and radioisotopes, infused intravenously, intragastrically or intraportally, were used to measure the conversion rates between arginine and its precursors proline, ornithine and citrulline. An arginine-deficient diet was used in all studies to create a metabolic state where there would be maximal stimulus for arginine synthesis. In enterally-fed piglets, the conversion rate [[mu]mol/(kg·h)] of circulating proline to arginine was greater in piglets receiving the arginine-deficient diet than in those receiving a generous intake of arginine (47 vs. 15; pooled SE 4) (P < 0.05); however, regardless of arginine intake, there was no arginine synthesis during first-pass hepatic metabolism. In parenterally-fed piglets receiving an arginine-deficient diet, the rate of arginine synthesis from circulating proline was directly related to mucosal mass (R2 = 0.72; P < 0.05); however, rates of synthesis [6-12 [[mu]mol/(kg·h)] were much lower than in enterally-fed piglets receiving a similar diet. In enterally-fed piglets, citrulline, but neither ornithine nor proline, addition to the arginine deficient diet was as effective as arginine addition in improving whole-body arginine status. The supplemental ornithine was extensively metabolized to carbon dioxide and proline. The limiting step in the conversion of proline to arginine was identified as citrulline formation, and this was not affected by arginine intake. Proline conversion to arginine represented 63% and 56% (pooled SE = 5%) of total arginine synthesis in enterally-fed piglets receiving generous and deficient intakes, respectively (P > 0.05). The whole-body rate of nitric oxide synthesis [[mu]mol/(kg·h)] was greater in piglets receiving the generous arginine diet than in those receiving the deficient arginine diet (105 vs. 46; pooled SE = 10) (P < 0.05), and this represents one possible way that supplemental arginine may prevent certain neonatal pathologies.
ISBN
9780494297575
0494297573