Enzyme-based assay for quantification of paraoxon in blood of parathion poisoned patients

1. Paraoxon concentration was estimated by means of inhibition kinetics observed with electric eel acetylcholinesterase (AChE) which was determined by a modified Ellman procedure. In human plasma, paraoxon was stabilized by inactivation of paraoxonase with EDTA and aluminon and by inhibition of butyrylcholinesterase with ethopropazine. Paraoxon (1-50 ng) was recovered at 86+/-1.7% (mean+/-s.e.m.) in ether extracts from 0.5 ml samples of spiked stabilized plasma. It could be stored without loss at - 20 degrees C for at least 1 month. 2. The enzyme-based assay was applied to follow the paraoxon plasma concentrations in three suicidal patients with severe parathion poisoning. In poisoning with excessive doses and initial paraoxon concentrations above 500 nM, therapeutic obidoxime concentrations of approximately 10 microM failed to essentially reactivate erythrocyte AChE in vivo, while reactivatability ex vivo was nearly complete. With the plasma concentrations of paraoxon dropping below 100 nM, however, reactivation by obidoxime became significant. Unexpectedly, paraoxon levels occasionally reincreased during treatment and resulted in re-inhibition of AChE, bearing some resemblance to the Intermediate Syndrome. 3. The paraoxon concentrations measured fitted satisfactorily the values calculated from the kinetic constants previously obtained for AChE inhibition and obidoxime-induced reactivation in vitro. This indicates that diethylphosphoryloxime formation during obidoxime-induced reactivation does not markedly contribute to the re-inhibition of AChE as observed in vitro.

Medienart:

Artikel

Erscheinungsjahr:

1998

Erschienen:

1998

Enthalten in:

Zur Gesamtaufnahme - volume:17

Enthalten in:

Human & experimental toxicology - 17(1998), 12 vom: 19. Dez., Seite 645-51

Sprache:

Englisch

Beteiligte Personen:

Eyer, F [VerfasserIn]
Eyer, P [VerfasserIn]

Themen:

4431-00-9
61G466064D
7WI4P02YN1
9G34HU7RV0
Aryldialkylphosphatase
Aurintricarboxylic Acid
Cholinesterase Inhibitors
Cholinesterase Reactivators
Diethylphosphoryloxime
EC 3.1.-
EC 3.1.8.1
Edetic Acid
Esterases
Journal Article
Oximes
Paraoxon
Parasympatholytics
Parathion
Phenothiazines
Profenamine
Q9CX8P80JW

Anmerkungen:

Date Completed 21.10.1999

Date Revised 14.02.2017

published: Print

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM09923260X