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In vitro sequestration of two organophosphorus homologs by the rat liver

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Relation http://ir.cftri.com/1256/
CB-01-99
 
Title In vitro sequestration of two organophosphorus
homologs by the rat liver
 
Creator Santhoshkumar, P.
Shivanandappa, T.
 
Subject 26 Pesticide Chemistry
17 Toxicology
 
Description Bromophos (Bp) and ethylbromophos (EBp) are two structurally homologous organophosphorus insecticides (OP) which show a 24-fold difference in their toxicity to the
laboratory rat (LD50—2215 and 91 mg:kg b.w., respectively). The role of rat liver in the
sequestration of the OP oxons was studied based on carboxylesterase (CaE) inhibition in vitro. Bromoxon (Bo) and ethylbromoxon (EBo) were greater inhibitors of rat hepatic CaE than brain acetylcholinesterase (AChE) with IC50 values at nanomolar and picomolar levels,
respectively. The capacity of the liver to sequester OPs was determined by measuring AChE inhibition pre-incubated with or without liver homogenate. AChE inhibition by Bo decreased with increasing concentration of liver tissue, whereas it was unaffected in the case of EBo.
The results imply that liver tissue contains binding sites, which sequester Bo thereby reducing
the number of OP molecules available to inhibit AChE. Although CaE inhibition leads to sequestration, other binding sites in the liver may have a significant role in determining the toxicity of OPs. Differential sequestration of the OPs by hepatic tissue, therefore, could be important in understanding the role of differential saturation of the target molecules, which
has a bearing on differential toxicity.
 
Date 1999
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://ir.cftri.com/1256/1/Chemico-Biological_Interactions_119-120_%281999%29_277-282.pdf
Santhoshkumar, P. and Shivanandappa, T. (1999) In vitro sequestration of two organophosphorus homologs by the rat liver. Chemico-Biological Interactions, 119-12. pp. 277-282.