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This Article Full Text (PDF) All Versions of this Article: jas.2008-1748v1 87/6/2073    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Greenwood, S. L. Articles by McBride, B. W. Search for Related Content PubMed PubMed Citation Articles by Greenwood, S. L. Articles by McBride, B. W.

Influence of glutamine infusion on ubiquitin, caspase-3, cathepsins L and B, and m-calpain expression in sheep with nutritionally induced metabolic acidosis

S. L. Greenwood^*, O. AlZahal^*, K. C. Swanson^*, J. C. Matthews and B. W. McBride^*

^* Department of Animal and Poultry Science, University of Guelph, Guelph, Canada N1G 2W1 Department of Animal and Food Sciences, University of Kentucky, Lexington, 40546

bmcbride{at}uoguelph.ca

Abstract

Provision of AA has shown success in attenuating proteolytic activity in monogastrics suffering from metabolic acidosis. However, it is unknown whether AA supplementation can provide any beneficial effects to ruminants with nutritionally induced metabolic acidosis. The objective of the current study was to examine the effects of glutamine infusion on various protein degradation components across a number of tissues in sheep with induced metabolic acidosis. Sheep were assigned to a randomized complete block design with 2 x 2 factorial arrangement of treatments (n = 6 sheep/treatment) consisting of a control diet or acidosis diet, and receiving a saline or L-glutamine infusion. Sheep were fed diets for 10 d and slaughtered on d 11. Liver, kidney, and muscle samples were collected at slaughter and examined for relative mRNA expression of ubiquitin, C8, E2, cathepsin L, cathepsin B, caspase-3, and m-calpain, as well as protein expression of ubiquitin. Relative mRNA expression of C8 (P = 0.02), E2 (P = 0.06), and ubiquitin (P = 0.07) was lower in kidney in acidotic versus control sheep. Additionally, mRNA expression of m-calpain in kidney was greater (P = 0.01) as a result of glutamine infusion. There were no significant alterations (P > 0.10) in mRNA of any component as a result of acidosis in the liver or muscle. This study demonstrates the inability of metabolic acidosis to increase expression of the ubiquitin-mediated proteolytic pathway in skeletal muscle; however, downregulation of renal mRNA expression of these components is apparent during the induction of metabolic acidosis.

Key Words: protein degradation • glutamine • metabolic acidosis • sheep