Measurement of Inhomogeneous Changes of Extracellular K⁺ Concentration Within the Ischemic Myocardium

Abstract

Using various types of ion-selective electrodes, it has been shown that the extracellular potassium concentration [K⁺]_e in the ischemic myocardium starts to increase within 15–20 s after acute coronary artery occlusion in both pigs [2, 3] and dogs [8]. [K⁺]_e in the ischemic myocardium was found to reach values of around 25 mMafter 60min of severe ischemia [6], The majority of these studies have measured [K⁺]_e in the center of the ischemic region of the left ventricle. We have recently performed studies in which epicardial [K⁺]_e was measured using ion-selective electrodes from the center of the ischemic zone outward over the border zone and into the nonischemic myocardium. The purpose of this study was to determine whether or not there is a homogeneous increase in [K⁺]_e within the ischemic myocardium, or whether there might be a potassium gradient from the center of the ischemic area out toward the normal myocardium.