Effect of Pantethine and Probucol on Cholesterol Metabolism in Rabbit Isolated Hepatocytes

Abstract

Pantethine and probucol are known to lower serum low density lipoprotein-cholesterol (LDL-C). Pantethine is reported to elevate high density lipoprotein-cholesterol (HDL-C). But probucol lowers HDL-C. The clinical significance of latter effect is still controversial. To evaluate whether combination of both agents prevent the lowered HDL-C by probucol, the effects of each agents alone and combinational effects on cholesterol metabolism in primary cultured hepatocytes were compared. Primary cultured hepatocytes were prepared from rabbit liver by collagenase treatments, and cultured in 10% FCS-DME medium containing 10^-7M insulin. LDL and HDL were prepared by ultracentrifugation from human serum. VLDL-cholesterol synthesis from [¹⁴C] acetate were analyzed with thin layer chromatography. For uptake study, LDL-[¹⁴C]cholesterol linoleate and HDL-[¹⁴C]cholesterol linoleate were incubated with hepatocytes for 8hrs. Secretion of bile acids was analyzed with degradative radioactivity form [³H]cholesterol, LDL or HDL-[¹⁴C] cholesterol linoleate. Both pantethine and probucol decreased synthesis of VLDL-lipid from [¹⁴C] acetate. Both agents increased LDL-C uptake into hepatocytes. Pantethine decreased incorporation of HDL-C, but probucol increased incorporation of HDL-C. These results were consistent with the serum lipoprotein changes observed in clinical studies. Combinational addition of pantethine and probucol to cultured hepatocyte decreased VLDL-C synthesis from acetate additively, and increased LDL-C incorporation, but decreased HDL-C incorporation. These results obtained from hepatocytes suggests that combination therapy may prevent HDL-C lowering effect of probucol.