Lipid composition and monooxygenase relationship in liver microsomal membranes from rats fed unbalanced diets

The cholesterol and phospholipid content of microsomal membrane from rats fed either a high lipid (Hl) (30% lard) or a low protein (Lp) diet (6% casein) have been compared with those from rats fed a standard (St) diet (22% casein, 5% lard). For each diet, half of the group was treated with Phenochlor DP6. A significant increase in the phospholipid cholesterol ratio was observed in rats fed a high lipid diet or treated with DP6. These effects tend to increase the microsomal membrane fluidity. The protein deficiency decreased the phospholipid/cholesterol ratio and then the fluidity of the endoplasmic reticulum membrane. The specific activity of cytochrome P-450 to hydroxylate aniline which is independent to the enzymic form of cytochrome P-450 was closely correlated with the viscosity status of the microsomal membrane.