Linked Life Data

3040756

Source:http://linkedlifedata.com/resource/pubmed/id/3040756

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
1987-10-21
pubmed:abstractText
The bidirectional flux of unesterified cholesterol between cells and high density lipoprotein (HDL) was studied in relationship to the binding of HDL to cells. At 100 micrograms at HDL protein/ml, the rate constant for cholesterol efflux from rat Fu5AH hepatoma cells is 3 X 10(-3)/min (t1/2 for efflux of 3.9 h), whereas efflux from GM3468 human fibroblasts is 0.075/4 h (equivalent to a t1/2 for efflux of 37 h). The relatively slow efflux of cholesterol from fibroblasts in comparison to rat hepatoma cells was observed previously with micellar and vesicular phospholipid-containing acceptors, which promote efflux by a mechanism involving the diffusion of cholesterol in the aqueous phase between the plasma membrane and the acceptor particles. When plotted against the logarithm of HDL concentration, the isotherms for efflux are centered at 300 and 100 micrograms of HDL protein/ml with the hepatoma cells and fibroblasts, respectively. These concentrations are 8-150 times greater than the corresponding values for Kd of specific HDL binding (2 and 12 micrograms of protein/ml, for hepatoma cells and fibroblasts, respectively). The treatment of HDL with tetranitromethane reduces the lipoprotein's affinity for specific cell-surface binding sites by 80-90%. However, at HDL concentrations of 5-60 micrograms of protein/ml, this treatment does not significantly inhibit cholesterol efflux from hepatoma cells, and inhibits efflux from fibroblasts an average of about 15%. Over the same range of concentrations, nitration alters influx by amounts less than 30% in the two cell types. These effects on flux do not parallel the reduced affinity of nitrated HDL for specific cell-surface binding sites. In summary, the present results do not support the concept that cholesterol transfer is facilitated by the specific cell-surface binding of HDL, but are consistent with the aqueous diffusion model of cholesterol transfer between cells and lipoproteins.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
262
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12557-64
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Cholesterol flux between cells and high density lipoprotein. Lack of relationship to specific binding of the lipoprotein to the cell surface.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't