Variability of alpha-tocopherol values associated with procurement, storage, and freezing of equine serum and plasma samples.
Recent evidence concerning the pathogenesis of equine degenerative myeloencephalopathy indicated that low blood alpha-tocopherol values are a factor in the disease process. Variables that could be introduced by a veterinarian procuring, transporting, or storing samples were evaluated for effects on alpha-tocopherol concentration in equine blood. These variables included temperature; light; exposure to the rubber stopper of the evacuated blood collection tube; hemolysis; duration of freezing time, with and without nitrogen blanketing; and repeated freeze/thaw cycles. It was found that hemolysis caused the greatest change in high-performance liquid chromatography-measured serum alpha-tocopherol values, with mean decrease of 33% (P < 0.001). Lesser, but significant (P < 0.01) changes in serum alpha-tocopherol values were an approximate 10% decrease when refrigerated blood was left in contact with the red rubber stopper of the blood collection tube for 72 hours and an approximate 5% increase when blood was stored at 20 to 25 C (room temperature) for 72 hours. Repeated freeze/thaw cycles resulted in a significant (P < 0.05) 3% decrease in alpha-tocopherol values in heparinized plasma by the third thawing cycle. Freezer storage for a 3-month period without nitrogen blanketing resulted in slight (2%) decrease in mean serum alpha-tocopherol values, whereas values in serum stored for an identical period under nitrogen blanketing did not change. A significant (P < 0.001) mean decrease (10.3%) in alpha-tocopherol values was associated with freezer (-16 C) storage of nitrogen blanketed serum for 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)
Craig
A M
AM
College of Veterinary Medicine, Oregon State University, Corvallis 97331.
Blythe
L L
LL
Rowe
K E
KE
Lassen
E D
ED
Barrington
R
R
Walker
K C
KC
D000704:Analysis of Variance; D000818:Animals; D001793:Blood Preservation / Q000662:veterinary*; D005615:Freezing; D006736:Horses / Q000097:blood*; D010949:Plasma / Q000737:chemistry; D015203:Reproducibility of Results; D009927:Tissue and Organ Procurement; D014810:Vitamin E / Q000097:blood*
D014810:Vitamin E