Low-salt diet alters the phospholipid composition of rat colonocytes

The effect of low-salt diet un phospholipid composition and remodeling was examined in rat colon which represents a mineralocorticoid target tissue. T o elucidate this question, male Wistar rats were fed a low-salt diet and dr ank distilled water (LS, low-salt group) or saline instead of water (HS, hi gh-salt group) for 12 days before the phospholipid concentration and fatty acid composition of isolated colonocytes were examined. The dietary regimen s significantly influenced the plasma concentration of aldosterone which wa s high in LS group and almost zero in HS group. Plasma concentration of cor ticosterone was unchanged. When expressed in terms of cellular protein cont ent, 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 phosph olipid 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 pe rcentage of phosphatidylinositol (P1), PS and cardiolipin (CL) were not aff ected by mineralocorticoid treatment. With respect to the major phospholipi ds (PE, PC), a higher level of n-6 polyunsaturated fatty acids (PUFA) and l ower levels of monounsaturated fatty acids were detected in PC of LS group. The increase of PUFA predominantly reflected an increase in arachidonic ac id 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 t hat alterations in phospholipid concentration and metabolism can be detecte d in rats with secondary hyperaldosteronism. The changes in phospholipid co ncentration and their fatty acid composition during fully developed effect of low dietary Na+ intake may reflect a physiologically important phenomeno n with long-term consequences for membrane structure and function.