Hydrogen peroxide exposure to bullfrog heart causes ST segment elevation

Ischemia-reperfusion injury is caused by reactive oxygen production after revascularization. It is characterized by elevated ST segments on electrocardiogram (ECG), although the mechanisms remain unknown. In the present study, we reproduced the ST segment changes observed during ischemia-reperfusion injury by exposing bullfrog hearts to hydrogen peroxide (H₂O₂). The ECG showed a marked elevation of the ST segments, and the action potential in cardiomyocytes demonstrated shortening of its duration. H₂O₂ exposure did not affect the abundance of K_ATP channel proteins. However, pharmacological blockade by glibenclamide significantly suppressed H₂O₂-induced changes in ECG and tended to suppress cardiac action potentials. K_ATP channel stimulation by H₂O₂ is thought to be responsible for generating an electrical difference in cardiomyocytes and the subsequent ST segment elevation.