Distribution of fatty acids among the different cardiac subcellular membranes in rats fed for 2 or 6 months diets containing either alpha-linolenic acid (LNA) or docosahexaenoic acid (DHA) or no n-3 PUFA

Brochot, Amandine; Abreu, S.; Macaire, Jean-Paul; Veili, P; Grynberg, Alain; Rousseau, Delphine

Distribution of fatty acids among the different cardiac subcellular membranes in rats fed for 2 or 6 months diets containing either alpha-linolenic acid (LNA) or docosahexaenoic acid (DHA) or no n-3 PUFA

2008

Previous work showed that the functional cardiac effect of dietary alpha-linolenic acid (LNA) is largely delayed (6 months) as compared to docosahexaenoic acid (DHA, 2 months) although the total cardiac membrane composition remained unchanged after 2 months. This delay could be due to specific reorganization of the different subcellular membrane fatty acid (FA) profile. In this study we investigated the evolution of FA composition between 2 and 6 months of diet in sarcolemmal (SL), mitochondrial (MITO), nuclear (NY) and sarcoplasmic reticulum (SR) membranes. Male Wistar rats were randomly assigned to three dietary groups (n = 10/diet/period), an n − 3 polyunsaturated-(PUFA)-free diet (CTRL), a LNA- and a DHA-rich diet. After 2 or 6 months of diet, subcellular cardiac membranes were separated by sucrose gradients and each membrane FA profile was analysed by gas chromatography (GC). As expected the n − 3 diets incorporated n − 3 PUFA instead of n − 3 PUFA in all the membranes, which also exhibited individual specificities. The diet duration increased SFA and decreased PUFA in SL, whereas NY remained quite constant. The SR and the MITO enriched in n − 3 PUFA exhibited a decreased DHA level with time in the DHA and CTRL groups. Conversely, the n − 3 PUFA level increased in the LNA group, mainly because of a significant DPA increase. We concluded that n − 3 PUFA diets lead to a better FA profile in all the investigated membranes (decrease n − 6/n − 3 ratio) and the delay in LNA effect may be related to a continued n − 3 enrichment of SR with time.

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