Membrane fatty acid composition of rat skeletal muscle is most responsive to the balance of dietary n-3 and n-6 PUFA

Abstract

The present study quantifies the relationships between diet fatty acid profile and fatty acid composition of rat skeletal muscle phospholipids. Young adult male Sprague-Dawley rats were fed, for 8 weeks, on one of twelve moderate-fat diets (25% of total energy) differing only in fatty acid profile. SFA content ranged from 8-88% of total fatty acids, MUFA 6-65%, total PUFA 4-81%, n-6 PUFA 3-70% and n-3 PUFA 1-70%. Diet PUFA included only essential fatty acids 18:2n-6 and 18:3n-3. The balance between n-3 and n-6 PUFA (PUFA balance) in the diet ranged from 1:99 to 86:14% n-3 PUFA:n-6 PUFA. The slope of muscle phospholipid composition plotted against diet composition quantifies the response of muscle membrane composition to dietary fat (0, no response; 1, complete conformity with diet). The resulting slopes were 002 (SFA), 010 (PUFA), 011 (MUFA), 014 (n-3 PUFA) and 023 (n-6 PUFA). The response to PUFA balance was biphasic with a slope of 098 below 10% diet PUFA balance and 016 above 10%. Thus, low diet PUFA balance has greater influence on muscle composition than 18-carbon n-3 or n-6 PUFA individually. Equations provided may allow prediction of muscle composition for other diet studies. Diet PUFA balance dramatically affects muscle 20:4n-6 and 22:6n-3. This may have significant implications for some disease states in human subjects.