No abstract

No abstract

Programmed electrical stimulation in anesthetized marmoset monkeys was used to examine relative antiarrhythmic efficacies of dietary n-3 and n-6 polyunsaturated fatty acids (PUFAs) from fish and plant oils. Diets contained 31% of energy (en%) as fat, comprising 15 en% saturated fat and 7 en% PUFAs, obtained by blending sheep fat with sunflower seed (SF/SSO) or fish oil (SF/FO) and a base diet. After 16-wk feeding, ventricular fibrillation (VF) was inducible in 6 of 10 animals on each diet under control conditions. The VF threshold (VFT) was significantly elevated in the SF/FO group (33.3 +/- 3.1 mA; n = 6) compared with the SF/SSO group (14.3 +/- 4.9 mA; n = 6). VFT, reduced during acute myocardial ischemia with 10 of 10 animals inducible per diet, remained significantly higher with SF/FO feeding. The SF/FO diet contained 3.8 en% as n-3 PUFAs, which was incorporated as 31% of myocardial membrane fatty acids. Dietary n-3 PUFA reduced vulnerability of normal or ischemic myocardium to arrhythmias in a nonhuman primate.

Coronary artery ligation (CAL) was used to produce an in vivo model of cardiac arrhythmias and myocardial infarction using anaesthetized male Hooded Wistar rats which had been fed for 6-7 or 18-20 months on either a standard reference diet alone or supplemented (12% w/w) with sunflower seed oil (linoleic acid rich) or sheep kidney fat (linoleic acid poor). The number of ventricular extra beats and duration of tachycardia or fibrillation in the 30-min postligation was increased in sheep kidney fat-fed rats. Infarct size 4 h postCAL was reduced in sunflower seed oil-fed rats. Arrhythmias, infarct size, and dietary-induced differences were increased with age. The diets employed produce changes in myocardial membrane phospholipids which could result in altered prostaglandin production. These results show that in the rat (as in man), age and dietary saturated fat are risk factors for sudden cardiac death and myocardial infarction and suggest that the rat is a useful model for the investigation of dietary interventions in heart disease.

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)