Comparative studies on composition of cardiac phospholipids in rats fed different vegetable oils |
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Authors: | J K G Kramer |
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Affiliation: | (1) Animal Research Institute, Research Branch, Agriculture, K1A OC6 Ottawa, Ontario, Canada |
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Abstract: | Male Sprague-Dawley rats were fed diets for 1 or 16 weeks, containing 20% by weight vegetable oils differing widely in their
oleic, linoleic and linolenic acid content. No significant changes were observed in the level of the cardiac lipid classes.
The fatty acid composition of the 2 major phospholipids, phosphatidylcholine and phosphatidylethanolamine, showed a remarkable
similarity between diets in the concentration of total saturated, C22 polyunsaturated and arachidonic acids. Monounsaturated
acids were incorporated depending on their dietary concentration, but the increases were moderate. Dietary linolenic acid
rapidly substituted C22 polyunsaturated fatty acids of the linoleic acid family (n−6) with those from the linolenic acid family
(n−3). The results suggest that dietary linolenic acid of less than 15% does not inhibit the conversion of linoleic to arachidonic
acid but the subsequent conversion of arachidonic acid to the C22 polyunsaturates was greatly reduced. Significant amounts
of dietary monounsaturated fatty acids were incorporated into cardiac cardiolipin accompanied by increases in polyunsaturated
fatty acids, apparently to maintain an average of 2 double bonds/molecule. The cardiac sphingomyelins also accumulated monounsaturated
fatty acids depending on the dietary concentration. It is quite evident from the results of this study that the incorporation
of oleic acid and the substitution of linolenic for linoleic acid-derived C22 polyunsaturated fatty acids into cardiac phospholipids
was related to the dietary concentration of these fatty acids and was not peculiar to any specific oil. Even though it is
impossible to estimate the effect of such changes in cardiac phospholipids on membrane structure and function, results are
discussed which suggest that the resultant membrane in the Sprague-Dawley male rat is more fragile, leading to greater cellular
breakdown and focal necrosis.
Contribution No. 914 from the Animal Research Institute. |
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