Journal of Lipid Research, Vol 26, 705-712, Copyright © 1985 by Lipid Research, Inc.
Specific binding of high density lipoprotein (HDL3) is not related to sterol synthesis in rat intestinal mucosa
A Kagami, NH Fidge and PJ Nestel
There is good evidence that high density lipoprotein (HDL) is involved in
the flux of cholesterol into the cells of some organs and out of the cells
of other tissues. Because we have previously found that HDL is bound
specifically by mucosal cells of the small intestine, we have examined the
possibility that this was associated with regulation of cholesterol flux.
We have, therefore, compared the specific binding of 125I-labeled HDL3 with
cholesterol synthesis in mucosal cells obtained from rats that had been
treated to alter intestinal cholesterol metabolism. The rate of sterol
synthesis measured in tissue slices, by the incorporation of [3H]water into
sterols, was altered up to fivefold by treatment with cholestyramine (to
induce bile salt loss), by surformer treatment (to reduce absorption of
cholesterol), and by biliary diversion. Yet the capacity of mucosal cells
to bind, internalize, and degrade 125I-labeled HDL3 was unchanged.
Cholesterol feeding influenced neither the interaction of 125I-labeled HDL3
with cells nor the rate of sterol synthesis. Furthermore, the interactions
of 125I-labeled HDL3 with mucosal cells isolated from the proximal and
distal halves of the intestine or between the upper and lower villus cells
were similar, despite differences in sterol synthesis. These data suggest
that, in rat intestine, the specific binding of HDL is not related to
sterol synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)