Colorimetric estimate of cholesterogenesis in livers perfused in the presence of trans-1,4-bis-(2-chlorobenzylaminomethyl)-cyclohexane dihydrochloride (AY-9944)

Abstract

AY-9944 ¦trans-1,4-bis-(2-chlorobenzylaminomethyl)-cyclohexane dihydrochloride¦ inhibits the conversion of sterol intermediates to cholesterol. The appearance of sterol intermediates, measured colorimetrically as “fast-acting” sterols, has been used as an estimate of hepatic cholesterogenesis in vivo after treatment with AY-9944. The appearance of fast-acting sterols as an estimate of cholesterogenesis was studied in the isolated rat liver, perfused in vitro in the presence of AY-9944, with or without oleic acid. Oleic acid elevated the appearance of fast-acting sterols in the liver and the perfusate. The secretion of fast-acting sterols by the perfused liver correlates with the activity ofmicrosomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of cholesterogenesis, and the synthesis of fast-acting sterols. The latter also correlates with the activity of HMG-CoA reductase. These observations are in agreement with previous reports of stimulation of the secretion and synthesis of cholesterol by liver perfused with oleic acid. Based on these findings, it is suggested that the level of fast-acting sterols after treatment with AY-9944 may be used as a colorimetric estimate for the synthesis and distribution of cholesterol in the isolated perfused rat liver.