Ascorbate increases the number of low density lipoprotein receptors in cultured arterial smooth muscle cells

Abstract

Receptor-mediated catabolism of low density lipoprotein (LDL) was increased 2-3-fold in down-regulated smooth muscle cells when the culture medium was supplemented with physiological concentrations of sodium ascorbate for 24 h. The enhanced degradation of LDL was associated with increased LDL receptor activity and LDL uptake. The increase in receptor activity was rapid, transient and inhibited by cycloheximide. Kinetic analysis of saturable binding indicated that ascorbate increased the number of LDL receptors but had no effect on the affinity of the lipoprotein for its receptor. Our data indicate that ascorbic acid may play a role in the regulation of plasma cholesterol levels by influencing LDL receptor number.