Acetyl- and pseudo-cholinesterase activities of plasma, erythrocytes, and whole blood in male beagle dogs using Ellman's assay.
Organophosphate and carbamate ester insecticides, main causes of pesticide poisoning, inhibit cholinesterase (ChE) enzymes. The aim of this study was to measure and compare baseline values for pseudocholinesterase and acetylcholinesterase (AChE) enzyme activities of different blood fractions in the dog to aid in diagnosis of anticholinesterase poisoning. After collecting blood samples from 23 6-24-mo-old male beagle dogs, Ellman's colorimetric assay was run on plasma, red blood cells (RBC), and whole blood fractions prepared in triplicate. The procedure described in a commercially available kit was applied to plasma and RBC. Hemolyzed whole blood fractions (final dilution 1:8) avoided the time-consuming and laborious separation of plasma and RBC. In addition to the kit substrate acetylthiocholine (ASCh), we used butyrylthiocholine (BSCh) as substrate. Whatever the substrate, ChE activity was lower in RBC than in other blood preparations. It was higher when using ASCh rather than BSCh as substrate (mean IU/L+/-SD): 563+/-144 and 303+/-45 respectively, in contrast to plasma (1640+/-310 and 2510+/-450). Whole blood enzyme activity did not differ significantly according to substrate: ASCh, 1590+/-190; BSCh, 1620+/-250) with a 2 to 3% within-day coefficient of variation. Enzyme activity was significantly lower in dogs <1-y old. This study confirms the low ChE activity in dog RBC compared to other species and other blood fractions. It shows that using whole blood instead of separating RBC from plasma minimizes the variability of ChE activity in the hemoglobin-rich fraction.
Ecole Nationale Vétérinaire, Toxicology Unit, Maisons-Alfort, France.
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M
Kolf-Clauw
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Jez
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C
Ponsart
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IS
Delamanche
D000110:Acetylcholinesterase / Q000097:blood*; D000818:Animals; D002091:Butyrylcholinesterase / Q000097:blood*; D004283:Dog Diseases / Q000139:chemically induced / Q000175:diagnosis; D004285:Dogs / Q000097:blood*; D004912:Erythrocytes / Q000201:enzymology*; D007306:Insecticides / Q000506:poisoning; D008297:Male; D009943:Organophosphorus Compounds; D010949:Plasma / Q000201:enzymology*; D011041:Poisoning / Q000175:diagnosis / Q000662:veterinary; D012016:Reference Values
D007306:Insecticides; D009943:Organophosphorus Compounds; D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase