On the Metabolism of Cholesterol in Rat Liver Homogenates

The metabolism of endogenous cholesterol was studied in fractions of liver homogenates obtained from rats that had received a single injection of [1,2‐3H]cholesterol 48 hours before preparation of the homogenates. The pattern of labeled products formed in incubations of the 800×g supernatant fluid, of the mitochondrial fraction, and of the 20,000×g supernatant fluid was essentially the same as that described in earlier investigations, in which the labeled cholesterol had been added to the homogenates in acetone solution or as an emulsion. The results are consistent with the view that a major pathway for the conversion of cholesterol into 5β‐cholestane‐3α,7α,12α‐triol involves the intermediate formation of cholest‐5‐ene‐3β,7α‐diol, 7α‐hydroxycholest‐4‐en‐3‐one, and 7α,12α‐dihydroxycholest‐4‐en‐3‐one.