Physicochemical Factors in the Distribution of Plasma Lipoprotein Subunits between the Plasma Lipoproteins and the Arterial Wall

Abstract

The structural and functional integrity of membranes and lipoproteins is determined, in part, by the physical state of the lipids which compose them (Linden et al., 1973; Morrisett et al., 1976; Small, 1976). Numerous in vitro studies have demonstrated that diverse hydrophobic and amphiphilic substances interact preferentially with specific lipid classes having well-defined physical states. The interaction of cholesterol with phospholipids is greatest when the lipid is at or above its gel to liquid crystalline transition temperature, T, (Verkleij et al., 1974; de Kruyff et al., 1974). In mixtures of phospholipids composed of sphingomyelin and phosphatidylcholine, cholesterol preferentially associated with the former regardless of the physical state of either lipid (Demel and de Kruyff, 1977). Thus, there is compelling chemical evidence that the association of cholesterol with phospholipids is determined by both the physical state of the lipid and its molecular structure.