Activation of Na⁺/K⁺-ATPase attenuates high glucose-induced H9c2 cell apoptosis via suppressing ROS accumulation and MAPKs activities by DRm217

Hyperglycemia is one of the major factors responsible for the myocardial apoptosis and dysfunction in diabetes. Many studies have proved that there is a close relationship between decreased Na⁺/K⁺-ATPase activity and diabetic cardiomyopathy. However, the effect of directly activated Na⁺/K⁺-ATPase on high glucose-induced myocardial injury is still unknown. Here we found that DRm217, a Na⁺/K⁺-ATPase's DR-region specific monoclonal antibody and direct activator, could prevent high glucose-induced H9c2 cell injury, reactive oxygen species (ROS) release, and mitochondrial dysfunction. High glucose-treatment decreased Na⁺/K⁺-ATPase activity and increased intracellular Ca²⁺ level, whereas DRm217 increased Na⁺/K⁺-ATPase activity and alleviated Ca²⁺ overload. Inhibition of Ca²⁺ overload or closing sodium calcium exchanger (NCX channel) could reverse high glucose-induced ROS increasing and cell injury. In addition, DRm217 could significantly attenuate high glucose-induced p38, JNK and ERK1/2 phosphorylation, which were involved in high glucose-induced cell injury and ROS accumulation. Our findings suggest that DRm217 may protect against the deleterious effects of high glucose in the heart. Prevention of high glucose-induced myocardial cell injury by specific Na⁺/K⁺-ATPase activator may be an attractive therapeutic option.