Linked Life Data

11558582

Source:http://linkedlifedata.com/resource/pubmed/id/11558582

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
2001-9-17
pubmed:abstractText
Repetitive administration of propranolol (PL) in rats decreases the activities of cytochrome P450 (CYP) 2D enzyme(s) in hepatic microsomes. We examined the properties of 4-hydroxypropranolol (4-OH-PL) as an inactivator of rat liver microsomal CYP2D enzyme(s) using bunitrolol (BTL) 4-hydroxylation and PL 5- and 7-hydroxylations as indices of CYP2D enzyme activity. Rat microsomal BTL 4-hydroxylase activity was inhibited by the addition of 4-OH-PL to the incubation medium. The inhibition was greater after preincubation of microsomes with 4-OH-PL in the presence of NADPH than in its absence. The type of inhibition kinetics of BTL 4-hydroxylase by 4-OH-PL was changed from a competitive type to a noncompetitive type by the preincubation. The inhibition of rat liver microsomal PL 5- and 7-hydroxylases by 4-OH-PL was blocked efficiently by co-incubation with quinine, a typical inhibitor of rat CYP2D enzyme(s), or to a lesser extent by BTL. However, quinidine, a diastereomer of quinine, did not significantly protect against the enzyme inactivation. The protective capacities of the substrate and inhibitors reflected their affinities for rat CYP2D enzyme(s). BTL hydroxylase was not affected by either 1,4-naphthoquinone or 1,4-dihydroxynaphthalene which are possible metabolites of 4-OH-PL. These results provide further evidence to support the notion that PL is biotransformed by rat CYP2D enzyme(s) to 4-OH-PL, which is further oxidized to a chemically reactive metabolite in the active site. The inactivation of CYP is likely the result of covalent binding of the reactive species to an amino acid residue of the active site.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0918-6158
pubmed:author
pubmed:issnType
Print
pubmed:volume
24
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
988-94
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol.
pubmed:affiliation
Laboratory of Health Chemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan. shizuo@pharm.okayama-u.ac.jp
pubmed:publicationType
Journal Article, In Vitro