Journal of Lipid Research, Vol 19, 433-442, Copyright © 1978 by Lipid Research, Inc.
Lipid synthesis in isolated intestinal cells
KM Shakir, SG Sundaram and S Margolis
Since the small intestine contributes significantly to serum cholesterol
and very low density lipoprotein levels, acute regulation of lipid
synthesis was investigated in isolated rat intestinal cells incubated in
Krebs-Ringer bicarbonate buffer with 5 mM glucose and [14c]acetate or 3H2O.
Incorporation of [14c]acetate into cellular lipids was 6- to 8-fold greater
in crypt than in villus cells. In both cell types the distribution of 14C
among the various lipid classes was as follows: 52.5% in triglycerides,
diglycerides, and monoglycerides; 22.3% in cholesterol; 8.3% in cholesteryl
esters; 1.9% in fatty acids; and 15.0% in phospholidpids. In contrast, the
medium lipids contained significantly higher amounts of tri-, di- and
monoglycerides (61.1%) and lower amounts of cholesteryl esters (2.3%) and
phospholipids (11.9%). After saponification, 2/3 of the recovered 3H2O was
in fatty acids and 1/3 in cholesterol. Ethanol (10 mM) tripled 3H2O
incorporation into cellular lipids but had no effect on [14c]acetate
incorporation. Epinephrine and norepinephrine (10 micron), glucagon (10
micron), dibutyryl cyclic AMP (1MM), dexamethasone (1 mM and 1 micron), and
cholera toxin (1 microgram/ml) did not affect [14c]acetate incorporation.
We concluded that ehtanol stimulates intestinal lipid synthesis; however,
in sharp contrast to their inhibition of lipid synthesis in hepatocytes and
adipocytes, catecholamines, glucagon, and dibutyryl cyclic AMP do not
inhibit lipid synthesis in intestinal cells.
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