[Effects of high-carbohydrate diet on VLDL-, HDL-, and apolipoprotein CII-receptor activities on liver parenchymal and non-parenchymal cells in rats].

We studied the functions of hepatic VLDL-, HDL-, and apolipoprotein (apo) CIII-receptors in the endogenous hypertriglyceridemic (HTG) rats induced by feeding a high-carbohydrate diet (HCD) (80% of total calories). Compared with the control rats (60% of total calories in CHO), the fasting plasma triglyceride (TG) levels of the rats fed on the CHO diet for 5 days increased by 113.4% (P < 0.025, n = 6), but HDL-C and total cholesterol concentrations decreased by 28.4% and 14.4% (P < 0.05, P < 0.05). The binding (Bmax) and uptake of 125I-labeled VLDL by liver non-parenchymal cells (NPC) from HTG rats decreased by 65.0% and 19.1% (P < 0.001, P > 0.05) respectively. The binding of 125I-labeled apoE-deficient HDL3 to the NPC also decreased significantly (-54.5%, P < 0.05). But the affinities (Ka) of the two receptors were prone to increasing. However, the activities of VLDL- and HDL-receptors on liver parenchymal cells didn't significantly change. Meanwhile, the specific binding of 125I-labeled apo CIII to NPC from HTG rats increased by 104.5% (P < 0.025). The results of this study suggest that hepatic VLDL- and HDL-receptors could be down- and up-regulated respectively in response to plasma lipoprotein concentrations in the high CHO dietary rats, and apo CIII-receptor might play an important role in regulating VLDL- and HDL-receptor activities.