Decreased Na+/K+-ATPase Activity and Altered Susceptibility to Peroxidation and Lipid Composition in the Erythrocytes of Metabolic Syndrome Patients with Coronary Artery Disease

Background: The increased generation of reactive oxygen species that occurs in the case of a metabolic syndrome (MetS) may be responsible for the increased oxidative injury to erythrocyte membranes in coronary artery disease (CAD). Therefore, we studied the effects of MetS on both indexes of oxidative damage and biochemical properties of erythrocyte membranes in CAD patients. Methods: We analyzed the markers of oxidative stress, Na+/K+-ATPase activity, total cholesterol content of erythrocyte membranes (CEM), and fatty acid compositions of the erythrocyte membrane in 82 patients with stable CAD and 39 non-CAD subjects. Results: The CAD patients had higher levels of CEM, membrane lipid peroxidation, erythrocyte superoxide dismutase (SOD) activity, and Na+/K+-ATPase activity compared with non-CAD subjects. The Na+/K+-ATPase activity was correlated negatively with membrane lipid peroxidation, and positively with the CEM. In CAD patients with MetS compared with those without MetS, we found that the membrane lipid peroxidation and CEM were increased, whereas the n-3 fatty acids content, SOD activity, Na+/K+-ATPase activity were decreased. Conclusion: These findings suggest an impairment of erythrocyte membrane biochemical properties in stable CAD patients as a consequence of oxidative injury that may contribute to the development of CAD. In addition, MetS may be related to increased oxidative injury to erythrocyte membranes.