Effects of high-fat diets on hepatic fatty acid oxidation in the rat. Isolation of rat liver peroxisomes by vertical-rotor centrifugation by using a self-generated, iso-osmotic, Percoll gradient.
1. Rat liver peroxisomal fractions were isolated in iso-osmotic Percoll gradients by using vertical-rotor centrifugation. The fractions obtained with rats given various dietary treatments were characterized. 2. The effect on peroxisomal beta-oxidation of feeding 15% by wt. of dietary fat for 3 weeks was investigated. High-fat diets caused induction of peroxisomal beta-oxidation, but diets rich in very-long-chain mono-unsaturated fatty acids produced a more marked induction. 3. Peroxisomal beta-oxidation induced by diets rich in very-long-chain mono-unsaturated fatty acids can oxidize such acids. Trans-isomers of mono-unsaturated fatty acids are oxidized at rates that are faster than, or similar to, those obtained with corresponding cis-isomers. 4. Rates of oxidation of [14-14C]erucic acid by isolated rat hepatocytes isolated from rats fed on high-fat diets increased with the time on those diets in a fashion very similar to that previously reported for peroxisomal beta-oxidation [see Neat, Thomassen & Osmundsen (1980) Biochem, J. 186, 369-371]. 5. Total liver capacities for peroxisomal beta-oxidation (expressed as acetyl groups produced per min) were estimated to range from 10 to 30% of mitochondrial capacities, depending on dietary treatment and fatty acid substrate. A role is proposed for peroxisomal beta-oxidation in relation to the metabolism of fatty acids that are poorly oxidized by mitochondrial beta-oxidation, and, in general, as regards oxidation of fatty acids during periods of sustained high hepatic influx of fatty acids.
D000818:Animals; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D003102:Colloids; D004041:Dietary Fats / Q000008:administration & dosage*; D005227:Fatty Acids / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008830:Microbodies / Q000187:drug effects / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D009940:Organoids / Q000378:metabolism*; D010084:Oxidation-Reduction; D011205:Povidone; D051381:Rats; D012822:Silicon Dioxide
D003102:Colloids; D004041:Dietary Fats; D005227:Fatty Acids; C016039:Percoll; D012822:Silicon Dioxide; D011205:Povidone