The composition of cardiac phospholipids in rats fed different lipid supplements

Abstract

Changes in dietary lipid intake are known to alter the fatty acid composition of cardiac muscle of various animals. Because changes in cardiac muscle membrane structure and function may be involved in the pathogenesis of arrhythmia and ischemia, we have examined the effects of dietary lipid supplements on the phospholipid distribution and fatty acid composition of rat atria and ventricle following 20 weeks feeding of diets supplemented with either 12% sunflower-seed oil or sheep fat. Neither lipid supplement produced significant changes in the proportions of cholesterol, total phospholipids or phosphatidylcholine, phosphatidylethanolamine or diphosphatidylglycerol,--the phospholipid classes that together account for more than 90% of the total phospholipids of rat cardiac muscle. Significant changes were found in the profiles of the unsaturated fatty acids of all 3 phospholipid components of both atria and ventricle. Although similar, the changes between these tissues were not identical. However, in general, feeding a linoleic acid-rich sunflower seed oil supplement resulted in an increase in the omega-6 family of fatty acids, whereas feeding the relatively linoleic acid-poor sheep fat supplement decreased the level of omega-6 fatty acids but increased the levels of the omega-3 family, resulting in major shifts in the proportions of these families of acids. In particular, the ratio of arachidonic acid: docosahexaenoic acid (20:4,omega-6/22:6,omega-3), which is higher in all phospholipids of atria than ventricle, is increased by feeding linoleic acid, primarily by increasing the level of arachidonic acid in the muscle membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in Fatty Acid Composition of the Cardiac Phospholipids of the Cotton-Eared Marmoset (<i>Callithrix jacchus</i>) after Feeding Different Lipid Supplements

“…Although subject to less seasonal or geographic variation in fatty acid composition than sheep fat, a single batch of freshly prepared SSO (per oxide value of 0.6) was obtained from the supplier to provide the linoleic-acid-rich supplement used throughout the study. The major fatty acid composi tion of both the MF and the SSO used in this study is given in table I. Supplementing the CMD with MF or SSO resulted in either a linoleic-acid-poor or a linoleic-acid-rich diet, similar to those diets used in our ear lier studies with rats [3,4].…”

“…Limited, Victoria, Australia, or rendered mutton fat (MF) collected from around the kidney region of mature sheep (more than 24 months old) by the South Australian Meat Corporation (SAMCOR), Adelaide, South Australia. These lipid supplements were incorporated into the diets at the time of pelleting by a method similar to that described previously [4], Because of seasonal and age differences in the composition of ruminant fat [Charnock and Russell, unpublished data], sufficient fat was obtained, purified and stored at -2 5 °C for use throughout the entire experimental period. Although subject to less seasonal or geographic variation in fatty acid composition than sheep fat, a single batch of freshly prepared SSO (per oxide value of 0.6) was obtained from the supplier to provide the linoleic-acid-rich supplement used throughout the study.…”

“…Ltd., Caringbah. New South Wales; 100 mg/kg body weight), and anesthetic ether administered by face mask, the chest opened, and the heart removed for dissection of the left ventricle and the right atrium, which were used for lipid analyses by the methods described previously [3,4], Statistical analysis of the data was carried out either by application of the Student's t test, or an anal ysis of variance for multiple comparisons between pairs (14].…”

“…Recent work in our labo ratory has shown that in male rats, altered dietary lipid intake leads to significant and lasting alterations in membrane-phospho lipid composition of cardiac muscles [3,4], For example, feeding rats a sunflower seed oil (SSO)-supplemented diet rich in Iinoleic acid surprisingly leads to a reduction in ventricu lar 18:2,n-6. The nomenclature for fatty acid identification refers to the carbon chain length of the fatty acid, the total number of double bonds and the number of carbon atoms from the last double bond to the methyl end of the molecule (n-%).…”

“…Suffi cient differences were found between the re sults obtained with marmosets and those pre viously found with the rat [3,4] to re-empha size the need for the careful selection of ani mal models and cautious evaluation of ex perimental data in cardiovascular research [ 10,11].…”