EFFECT OF VARIOUS N-3 N-6 FATTY-ACID RATIO CONTENTS OF HIGH-FAT DIETSON RAT-LIVER AND HEART PEROXISOMAL AND MITOCHONDRIAL BETA-OXIDATION/

The present work extends tissue investigations previously performed in rat gastric mucosa on lipid metabolism alterations caused by n - 3 an d n - 6 fatty acid-enriched diets [13-15]. Liver and heart tissues are here studied and demonstrated to undergo, upon exposure to high fat d iets with various n - 3/n - 6 fatty acid ratio contents, biochemical a nd morphological changes which may be enumerated as follows: (1) Rat l iver peroxisomal prostaglandin E2, fatty acid but not bile acid beta-o xidation rates are enhanced, especially upon the diet with the higher n - 3/n - 6 fatty acid ratio. Mitochondrial beta-oxidation rates are l ittle or not affected by the high fat diets. (2) Rat liver carnitine a cyltransferases are stimulated by the high fat diets, the more rich th e n - 3 fatty acid content, the more pronounced the stimulatory effect . (3) Rat heart peroxisomal and mitochondrial beta-oxidation rates wer e increased in animals receiving the n - 3 fatty acid-enriched diet. A t a low n - 3/n - 6 fatty acid ratio content of the diet, these oxidiz ing rate values were in control range. The carnitine acyltransferase a ctivities were increased in rat heart to different extents, depending on the n - 3/n - 6 fatty acid ratio content of the diet. (4) Ultrastru ctural examination and morphometric determinations on hepatocytes from rats receiving the diets with the lowest and the highest n - 3/n - 6 fatty acid ratio contents disclose that in the latter case the numbers and fractional volumes of peroxisomes and mitochondria are significan tly higher than in the former case.