Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The disposition of the organophosphate anticholinesterase, diisopropylfluorophosphate (DFP), was studied in guinea pigs after inhalation exposure. The tissue disposition of [3H]DFP and its metabolites was determined in the major tissues of the guinea pig from 5 min to 24 hr after treatment. [3H]DFP rapidly penetrated all tissues, where it was quickly hydrolyzed to the inactive metabolite, free [3H]diisopropylphosphoric acid ([3H]DIP), or was covalently bound to tissue in the form of bound [3H]DIP. Tissue concentrations of [3H]DFP and free [3H]DIP followed a biphasic curve, with an initial phase representing a very rapid decrease in tissue concentrations, followed by a slower phase of tissue clearance. Concentrations of free [3H]DIP generally exceeded those of [3H]DFP; however, by 4 hr the greater portion of the radioactivity in all the tissues was in the form of bound [3H]DIP. Bound [3H]DIP levels did not follow a biphasic clearance curve and declined at a slower rate than [3H]DFP and free [3H]DIP tissue levels. By 5 min the greatest accumulation of bound [3H]DIP occurred in the liver (nearly 20% of the total body burden), with a noticeably small amount in the brain (0.1%). Tissue concentrations of nonextractable radioactivity, thought to be [3H]monoisopropylphosphoric acid ([3H]MIP), were appreciable and persistent throughout the time course. Total cholinesterase activity in the brain and red blood cells was inhibited by about 90%, with plasma pseudo- and true cholinesterase activity inhibited by 99 and 97%, respectively. The time course of recovery of enzyme activity in these tissues failed to correlate with the respective tissue levels of either bound [3H]DIP or [3H]MIP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The disposition of [3H]diisopropylfluorophosphate in guinea pigs after inhalation. 290 19

The biodisposition of [3H]diisopropylfluorophosphate (DFP) and its metabolites was studied in mice after inhalation administration. In addition, the time course of DFP-induced cholinesterase inhibition in selected tissues, hypothermia, and motor coordination were studied to determine a possible correlation with [3H]DFP, or its metabolites. The time course of tissue concentrations of [3H]DFP showed that [3H]DFP rapidly penetrated all tissues and was quickly hydrolyzed to [3H]diisopropylphosphoric acid (free [3H]DIP) or was covalently bound to tissue (bound [3H]DIP). By 1 hr, the greater portion of the radioactivity was in the form of bound [3H]DIP. Cholinesterase inhibition in brain, lung, diaphragm, and plasma was temporally related to concentrations of bound [3H]DIP between 5 min and 1 day, except at early time points for the lung. Motor incoordination (rotarod test) produced by DFP exposure had a rapid onset, with complete recovery by 10 hr. DFP-induced hypothermia (rectal temperature) had a very similar time-course profile to that of motor incoordination. The time course of hypothermia and motor incoordination was correlated with neither free [3H]DFP nor bound [3H]DIP concentrations in the brain, nor with cholinesterase inhibition in brain. These findings suggest that non-cholinesterase bound [3H]DIP may contribute to the depression of these centrally mediated effects.
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PMID:Relationship between the pharmacological effects and the biodisposition of [3H]diisopropylfluorophosphate in mice after inhalation. 403 91