Oxidized LDL from subjects with different dietary habits modifies atherogenic processes in endothelial and smooth muscle cells

Low-density lipoprotein (LDL) activates a number of processes involved in a therogenesis and vasoconstriction. Evidence suggests that oxidation increas es the atherogenicity of LDL. We investigated the effects of oxidized LDL ( ox-LDL) on cytotoxicity, prostacyclin (PGI(2)), and cyclic guanosine-3 ',5' -monophosphate (cGMP) production in rat vascular smooth muscle cell (VSMC) and rat heart endothelial cell (EC) culture, as well as EC- and VSMC-mediat ed LDL oxidation. Native LDL (n-LDL) was isolated from subjects on three lo ng-term diets with differing fatty acid content (control diet rich in satur ated fat and vegetarian and fish diets). The Cu2+-catalyzed oxidation of n- LDL was monitored using conjugated diene formation and stopped at various t ime points to achieve 20%, 45%, 70%, and 100% levels of ox-LDL. The lag pha se of oxidation by Cu2+ was shortest and thiobarbituric acid-reactive subst ance (TBARS) formation by VSMC-mediated oxidation was highest with n-LDL ob tained from the fish diet group. There were no differences between the ox-L DLs obtained from the different diet groups in their cytotoxicity in EC cul ture. The degree of oxidation did not influence LDL cytotoxicity. In VSMC c ulture PGI(2) production was increased by ox-LDLs from all diet groups. In EC culture only the extensively oxidized LDLs obtained from the vegetarian diet group were able to induce PGI(2) production. The LDLs did not affect b asal cGMP production in either EC or VSMC culture.