Effect of the Ethyl Ester and Sodium Salt of α- p -Chlorophenoxyisobutyric Acid on Cholesterol Oxidation by Rat Liver Mitochondria 1,2

Abstract

Summary

Mitochondrial preparations from livers of rats fed 0.3% ethyl α-p-chlorophenoxyisobutyrate (CPIB) show an increased capacity to oxidize cholesterol-26-¹⁴C to ¹⁴CO₂. When oxidation is calculated per milligram of mitochondrial nitrogen, oxidation of cholesterol by mitochondria from CPIB-fed rats is the same as that observed in normal rat liver mitochondria. In the absence of the boiled supernatant cofactor (cytosol) the mitochondria from CPIB-treated rats show a significantly higher capacity for cholesterol oxidation than do normal mitochondrial preparations. Mitochondria prepared from livers of rats fed sodium α-p-chlorophenoxyisobutyrate also oxidize more cholesterol than do control preparations. Fasting of the rats for 18 hr prior to mitochondrial preparation does not affect the extent of oxidation either in the presence or absence of cytosol. Mitochondrial preparations from CPIB-fed mice also oxidize more cholesterol than do controls. Studies of mitochondrial acid phosphatase and β-glucuronidase activity suggest that the increased oxidation of cholesterol is not due to lysosomal activity. Feeding of either the ethyl ester or sodium salt of α-p-chlorophenoxyisobutyric acid causes increase in liver size and usually an increase in liver triglyceride levels, confirming results of others.