Oxidized Low-Density Lipoprotein Associates with Ventricular Stress in Young Adults and Triggers Intracellular Ca(2+) Alterations in Adult Ventricular Cardiomyocytes.

Oxidized low-density lipoprotein (oxLDL) is associated with cardiac damage and causes injury to multiple cell types. We aimed to investigate the role of oxLDL in ventricular stress. We first examined the association between circulating oxLDL and N-terminal pro-brain natriuretic peptide (NT-proBNP), a marker of myocardial stress, in young subjects (30-50 years) with or without stable coronary artery disease (SCAD). oxLDL and NT-proBNP were significantly higher in subjects at high cardiovascular risk (CVR) than in subjects at low CVR and were associated independently of traditional CVR factors and C-reactive protein. Furthermore, the levels of oxLDL and NT-proBNP were significantly lower in subjects with SCAD than in peers at high CVR. To determine the intracellular mechanisms involved in the cardiac effects of oxLDL, we analyzed the in vitro effect of oxLDL on intracellular Ca(2+) handling in adult rat ventricular cardiomyocytes using confocal microscopy. Acute challenge of adult ventricular cardiomyocytes to oxLDL reduced systolic Ca(2+) transients and sarcoplasmic reticulum Ca(2+) load. Moreover, diastolic spontaneous Ca(2+) leak increased significantly after acute exposure to oxLDL. Thus, we demonstrate that oxLDL associates with NT-proBNP in young subjects, and can directly induce Ca(2+) mishandling in adult ventricular cardiomyoyctes, predisposing cardiomyocytes to cardiac dysfunction and arrhythmogenicity.