Physiol. Res. 49: 197-205, 2000

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


© 2000 by the Institute of Physiology, Czech Academy of Sciences