Linked Life Data

3610047

Source:http://linkedlifedata.com/resource/pubmed/id/3610047

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1987-8-28
pubmed:abstractText
Two types of models have recently been proposed to describe hepatic uptake kinetics of protein bound drugs: a model in which dissociation from plasma protein is rate limiting the process, and a model in which an interaction between protein and hepatocyte surface is thought to promote dissociation and uptake of the drug. This study was designed to investigate several aspects of both models, using lactosylated albumin as a binding protein that can interact with the Ashwell receptor abundantly present on the hepatocyte. Dibromosulfophthalein clearance was studied in rat liver in the presence of 150 microM (1%) albumin or 150 microM lactosylated albumin. Initial disappearance rate from perfusate in the presence of lactosylated albumin indicated a 2-fold decrease in hepatic uptake rate compared with native albumin. This was confirmed by compartmental analysis, showing a similar decrease in hepatic uptake rate constant. Protein binding of dibromosulfophthalein to lactosylated albumin was only marginally different from normal albumin. Consequently, modification of the protein retarded uptake of the organic anion at an essentially unchanged unbound concentration. Fluorescence spectroscopy of lactosylated albumin showed a blue-shifted tryptophan emission spectrum compared with albumin, indicating increased hydrophobicity of the neoglycoprotein. We therefore considered a change in off-and-on rate for binding of dibromosulfophthalein in lactosylated albumin. Rapid filtration experiments indicated that the dissociation rate constant of dibromosulfophthalein from lactosylated albumin was half that of controls. We conclude that the decreased off-rate from lactosylated albumin can explain the retarding influence on hepatic uptake rate of dibromosulfophthalein. This observation argues for the concept of dissociation-limited uptake in the hepatic clearance of the organic anion.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0270-9139
pubmed:author
pubmed:issnType
Print
pubmed:volume
7
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
688-95
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:articleTitle
Lactosylation of albumin reduces uptake rate of dibromosulfophthalein in perfused rat liver and dissociation rate from albumin in vitro.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't