Linked Life Data

1246012

Source:http://linkedlifedata.com/resource/pubmed/id/1246012

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1976-3-30
pubmed:abstractText
The metabolism of 8-14C-theophylline (14C-Theo) was investigated in vivo and in vitro in the rat. In vivo, 14C-Theo at an initial blood concentration of 10muM was metabolized to at least two different metabolites, 1,3-dimethyl uric acid and 1-methyl uric acid. The biological half-life of the 8-14C-Theo (6 +/- 1.5 hours) was determined from the urinary excretion of radioactivity. Ten days of oral pretreatment of rats with theophylline resulted in a faster rate of metabolism of both 14C-Theo and zoxazolamine. In vitro metabolism of 14C-Theo was investigated in order to identify the enzyme(s) responsible for theophylline metabolism. A tissue survey utilizing tissue slices demonstrated that the metabolism is localized only in the liver since slices of heart, lung, intestine, brain, adrenals, kidney or spleen did not metabolize 14C-Theo. 14C-Theo metabolism in the liver was localized in the subcellular fraction of microsomes and not in the mitochondria or cytosol. 14C-Theo metabolism by liver slices or liver microsomes was inhibited by typical liver microsomal inhibitors such as 2-diethylaminoethyl-2,2-diphenylvalerate (SKF 525-A) and 3-methyl-4-methylaminoazobenzene. 14C-Theo metabolism in liver slices was increased by the liver microsomal-inducing agents, phenobarbital and 3-methylcholanthrene. 3-Methylcholanthrene also increased 14C-Theo metabolism by the liver microsomal fraction. One of the metabolites, 1-methylxanthine, generated by the microsomal system, is a substrate for xanthine oxidase, and its conversion to 1-methyl uric acid by xanthine oxidase was blocked by allopurinol. 14C-Theo per se was shown not to be a substrate for liver xanthine oxidase or aldehyde oxidase. These results indicate that Theo per se is metabolized by the liver microsomal system and not by liver xanthine oxidase or aldehyde oxidase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
196
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
213-25
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Theophylline metabolism by the rat liver microsomal system.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.