In vitro subcellular characterization of flunixin liver metabolism in heifers, steers, and cows

The majority of cattle found to have violative liver residues of flunixin (FNX) in the United States are dairy cows. It has been hypothesized that illness of cows decreases the rate of FNX metabolism, resulting in violative residues at slaughter. Another contributing factor might be an age-related d...

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Bibliographic Details
Published in:Research in veterinary science 2019-04, Vol.123, p.118-123
Main Authors: Shappell, Nancy W., Duke, Sarah E., Bartholomay, Kathryn A.
Format: Article
Language:English
Subjects:
5-OH Flunixin
Age
Animal lactation
Antibiotics
Banamine
beef cattle
Cattle
Cytochrome
cytochrome P-450
Cytochrome P450
Cytochromes P450
Dairy cattle
dairy cows
Dehydrogenases
enzyme activity
Enzymes
Females
flunixin
Gender
Glucose 6 phosphate dehydrogenase
glucose 6-phosphate
Glucosephosphate dehydrogenase
heifers
Inflammation
LC-MSMS
Liver
Males
Metabolism
Metabolites
Microsome
Milk
Milk production
NADP
NADPH-Cytochrome P450 Reductase
Proteins
Reductase
Residues
Slaughter
steers
subcellular fractions
United States
Veterinary medicine
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Summary:The majority of cattle found to have violative liver residues of flunixin (FNX) in the United States are dairy cows. It has been hypothesized that illness of cows decreases the rate of FNX metabolism, resulting in violative residues at slaughter. Another contributing factor might be an age-related decrease in FNX metabolism, as dairy cull cows are typically older at slaughter than cattle raised for beef, rather than milk production. In order to investigate this possibility, subcellular fractions were prepared from liver slices from steers (n = 6) and heifers (n = 5) 48 mos of age. Cytochrome P450 (P450), NADPH-P450 reductase and glucose-6-phosphate dehydrogenase (G6PDH) activity and rate of 5-hydroxy FNX (5-OH FNX) formation were measured in liver homogenate, cytosolic, microsomal, and S9 fractions. Cows had lower concentrations of P450, NADPH-P450 reductase activity, and 5-OH FNX formation (P ≤ 0. 02), supporting the theory that advanced age may contribute to the higher incidence of violative FNX residues in dairy cows. •In vitro liver microsomal metabolism of flunixin ↓ in cows vs heifers and steers•[P450] and NADPH-Cytochrome P450 reductase ↓ in cows•Primary metaboite 5-OH flunixin
ISSN:0034-5288
1532-2661
DOI:10.1016/j.rvsc.2018.12.012