title: Potassium efflux from myocardial cells induced by defibrillator shock.
abstract: A transient, dose-dependent cardiac depression was produced by defibrillator shocks in an isolated, working canine heart preparation perfused with oxygenated arterial blood from a support dog. Accompanying this depression was an efflux of potassium (K+), forced out of the myocardial cells by the passage of defibrillating current. The transient increase in extracellular K+ concentration was recorded graphically in the venous outflow. It was found that 5-msec rectangular wave shocks, from three to ten times defibrillatory current threshold, released dose-related pulses of K+. It is concluded that because K+ is a myocardial depressant, at least part of the myocardial depression after defibrillation is caused by the release of K+ from the myocardial cells.
mesh_terms: D000818:Animals; D004285:Dogs; D004554:Electric Countershock / Q000009:adverse effects; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D011188:Potassium / Q000378:metabolism*
chemical_list: D011188:Potassium