Relation between lipoprotein (a) and in vitro oxidation of apolipoprotein B-containing lipoproteins

Objectives: To assess the relationship between lipoprotein (a) [Lp (a)] and lipoprotein oxidation in patients with coronary artery disease (CAD). Design and methods: Oxidation of apolipoprotein (apo)B-containing lipoprote ins, vitamin E, carotenoids, lipid-lipoprotein levels were determined in 17 1 CAD and 70 non-CAD subjects. Results: In CAD patients with Lp (a) concentrations greater than or equal t o 30 mg/dL; total cholesterol (TC), low density lipoprotein cholesterol (LD L-C), malondialdehyde (MDA), and apo B levels were significantly higher and lag-time and age were significantly lower than those of CAD patients with Lp (a) concentrations < 30 mg/dL. In non-CAD subjects with Lp (a) concentra tions a 30 mg/dL; TC, LDL-C, and vitamin E levels were significantly higher and lag-time was significantly lower than those of non-CAD subjects with L p (a) concentrations < 30 mg/dL. In CAD patients, Lp (a) correlated negativ ely with lag-time and positively with MDA levels. Lp (a) correlated negativ ely with lag-time and vitamin E levels in non-CAD subjects. Conclusions: We have shown that plasma apo B-containing lipoproteins of bot h CAD and non-CAD subjects with Lp (a) levels 30 mg/dL are more susceptible to in vitro oxidative modification than those of subjects with Lp (a) leve ls < 30 mg/dL. The relationship between Lp (a) and enhanced susceptibility of apo B-containing lipoproteins to oxidation, appears to support routine i nvestigation of Lp (a). Copyright (C) 2000 The Canadian Society of Clinical Chemists.