Diets varying in linoleic and linolenic acid content alter liver plasma membrane lipid composition and glucagon-stimulated adenylate cyclase activity.

Male Sprague-Dawley rats were fed diets varying in fatty acid composition for 24 d. Liver plasma membranes were isolated, and the effect of diet on phospholipid fatty acyl tail composition and glucagon-stimulated adenylate cyclase activity was measured. Dietary linolenic acid influenced membrane phospholipid fatty acid composition and altered the effect of different dietary levels of linoleic acid on membrane composition. At low dietary intakes of linolenic acid, membrane fatty acids derived from linolenic acid increased as dietary intake of C18:2(9,12) increased. At high dietary linolenic acid levels membrane content of fatty acids derived from linolenic acid decreased as dietary intake of linoleic acid increased. Glucagon-stimulated adenylate cyclase activity decreased at high levels of both dietary linoleic acid and linolenic acid. These observations suggest that dietary balance between linoleic and linolenic acids has a role in plasma membrane composition and may control glucagon-stimulated adenylate cyclase activity.