Low-Salt Diet Alters the Phospholipid Composition of Rat Colonocytes
L. Mrnka1, O. Nováková2, F. Novák3, E.
Tvrzická4 , J. Pácha1
1Institute of Physiology, Czech Academy of Sciences, 2Department
of Animal Physiology, Faculty of Sciences, 3Department of
Biochemistry, Faculty of Sciences, Charles University and 4Fourth
Department of Medicine, First Faculty of Medicine, Charles University, Prague,
Czech Republic
Received November 22, 1999
Accepted January 20, 2000
Summary
The effect of low-salt diet on phospholipid composition and
remodeling was examined in rat colon which represents a mineralocorticoid target
tissue. To elucidate this question, male Wistar rats were fed a low-salt diet
and drank distilled water (LS, low-salt group) or saline instead of water (HS,
high-salt group) for 12 days before the phospholipid concentration and fatty
acid composition of isolated colonocytes were examined. The dietary regimens
significantly influenced the plasma concentration of aldosterone which was high
in LS group and almost zero in HS group. Plasma concentration of corticosterone
was unchanged. When expressed in terms of cellular protein content, a
significantly higher concentration of phospholipids was found in LS group, with
the exception of sphingomyelin (SM) and phosphatidylserine (PS).
Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) accounted for more
than 70 % of total phospholipids in both groups. A comparison of phospholipid
distribution in LS and HS groups demonstrated a higher percentage of PE and a
small, but significant, decrease of PC and SM in LS group. The percentage of
phosphatidylinositol (PI), PS and cardiolipin (CL) were not affected by
mineralocorticoid treatment. With respect to the major phospholipids (PE, PC), a
higher level of n-6 polyunsaturated fatty acids (PUFA) and lower levels of
monounsaturated fatty acids were detected in PC of LS group. The increase of
PUFA predominantly reflected an increase in arachidonic acid by 53%. In
comparison to the HS group, oleic acid content was decreased in PC and PE
isolated from colonocytes of the LS group. Our data indicate that alterations in
phospholipid concentration and metabolism can be detected in rats with secondary
hyperaldosteronism. The changes in phospholipid concentration and their fatty
acid composition during fully developed effect of low dietary Na+
intake may reflect a physiologically important phenomenon with long-term
consequences for membrane structure and function.
Key words
Aldosterone · Fatty acids ·
Phospholipid metabolism
Reprint requests
Jiří Pácha, Institute of Physiology, Czech Academy of
Sciences, Vídeňská 1083, 142 20 Prague 4 - Krč, Czech Republic. e-mail: pacha@biomed.cas.cz
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