Dietary fat ratios and liver plasma membrane lipid composition.
Male Sprague-Dawley weanling rats were fed isocaloric diets consisting of 10% (by wt) fat. The six groups differed in the ratio of corn oil and butter fat present in the diets such that: 10C, 10% corn oil (C); 8C2B, 8% C/2% butter fat (B); 6C4B, 6% C/4% B; 4C6B, 4% C/6% B; 2C8B, 2% C/8% B; and 10B, 10% B. Liver plasma membranes were analyzed for fatty acid composition and cholesterol/phospholipid molar ratio. The 18:2n-6 content was constant in the 10C and 8C2B diets and then decreased linearly through the 2C8B diet. The 20:4n-6 and 18:1n-9 contents were constant except in the 10B diet, in which a significant decrease and increase, respectively, were observed. The cholesterol/phospholipid molar ratio increased between the 10C and 6C4B diets and subsequently (4C6B and 10B diets) remained constant. This data indicates that changes in n-6 fatty acid content in the liver plasma membrane are directly related to dietary intake only for 18:2n-6. Arachidonic acid content in the membrane is maintained at a constant level until the linoleic acid content of the diet is reduced to 0.5% of calories. It also indicates that the cholesterol content of the membrane becomes saturated and does not increase with increasing concentrations of saturated fat in the diet.
Hamm
M W
MW
Department of Nutrition, Rutgers University, New Brunswick, NJ 08903.
Sekowski
A
A
Ephrat
R
R
D000818:Animals; D002462:Cell Membrane / Q000032:analysis; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D008099:Liver / Q000032:analysis*; D008297:Male; D008563:Membrane Lipids / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains
D004041:Dietary Fats; D005227:Fatty Acids; D008563:Membrane Lipids