title: Factors in standardizing automated cholinesterase assays.
abstract: A scientific panel assembled by the U.S. Environmental Protection Agency (EPA) determined that variability in cholinesterase (ChE) activities in the agency's pesticide/animal study database likely was due to a lack of accepted guidelines for ChE methodology. A series of trials was held in which participating laboratories measured ChE activity in blood and brain samples from untreated and pesticide-treated rats using a colorimetric assay method. The degree of inhibition of ChE activity in plasma and brain samples compared to controls was consistent among most of the laboratories. The ChE activity in erythrocyte samples differed more between laboratories due to a high blank, low erythrocyte AChE activity and hemoglobin absorption at the wavelength of the assay. Strategies are suggested for minimizing the variability of ChE activity in hemoglobin-rich samples.
authors.affiliation: Department of Environmental Toxicology, University of California, Davis, USA.
authors.forename: B W
authors.initials: BW
authors.lastname: Wilson
authors.forename: S
authors.initials: S
authors.lastname: Padilla
authors.forename: J D
authors.initials: JD
authors.lastname: Henderson
authors.forename: S
authors.initials: S
authors.lastname: Brimijoin
authors.forename: P D
authors.initials: PD
authors.lastname: Dass
authors.forename: G
authors.initials: G
authors.lastname: Elliot
authors.forename: B
authors.initials: B
authors.lastname: Jaeger
authors.forename: D
authors.initials: D
authors.lastname: Lanz
authors.forename: R
authors.initials: R
authors.lastname: Pearson
authors.forename: R
authors.initials: R
authors.lastname: Spies
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood / Q000378:metabolism; D000122:Acetylthiocholine / Q000378:metabolism; D000818:Animals; D001681:Biological Assay; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D012721:Carbaryl / Q000633:toxicity; D004390:Chlorpyrifos / Q000633:toxicity; D002800:Cholinesterase Inhibitors / Q000633:toxicity; D002802:Cholinesterases / Q000097:blood / Q000378:metabolism*; D002863:Chromogenic Compounds / Q000737:chemistry; D003124:Colorimetry / Q000592:standards; D004228:Dithionitrobenzoic Acid / Q000737:chemistry; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology*; D017408:Guidelines as Topic; D006868:Hydrolysis; D007306:Insecticides / Q000633:toxicity; D009525:Niacin / Q000031:analogs & derivatives / Q000737:chemistry; D010865:Pilot Projects; D051381:Rats; D015203:Reproducibility of Results; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D002800:Cholinesterase Inhibitors; D002863:Chromogenic Compounds; D007306:Insecticides; C099658:dithionicotinic acid; D009525:Niacin; D000122:Acetylthiocholine; D004228:Dithionitrobenzoic Acid; D000110:Acetylcholinesterase; D002802:Cholinesterases; D004390:Chlorpyrifos; D012721:Carbaryl