Partial exposure of frog heart to high-potassium solution: an easily reproducible model mimicking ST segment changes.

By simply inducing burn injuries on the bullfrog heart, we previously reported a simple model of abnormal ST segment changes observed in human ischemic heart disease. In the present study, instead of inducing burn injuries, we partially exposed the surface of the frog heart to high-potassium (K+ ) solution to create a concentration gradient of the extracellular K+ within the myocardium. Dual recordings of ECG and the cardiac action potential demonstrated significant elevation of the ST segment and the resting membrane potential, indicating its usefulness as a simple model of heart injury. Additionally, from our results, Na+ /K+ -ATPase activity was thought to be primarily responsible for generating the K+ concentration gradient and inducing the ST segment changes in ECG.