Shortening of monophasic action potential duration during hyperkalemia and myocardial ischemia in anesthetized dogs

Japanese Journal of Pharmacology
K HamadaT Nagao

Abstract

The elevation of the myocardial extracellular potassium concentration ([K+]o) is known to shorten action potential duration, which may lead to the occurrence of arrhythmias. The aim of this study was to compare the mechanisms responsible for the shortening of monophasic action potential duration (MAPD) in hyperkalemic and myocardial ischemic hearts in anesthetized dogs. During a venous infusion of KCl for 5 min, [K+]o was increased and MAPD was significantly shortened. The ATP-sensitive K+ (K[ATP]) channel blocker glibenclamide did not affect the shortening of MAPD during KCl-infusion, indicating that K(ATP) channels are not involved in this mechanism. During 5-min occlusion of the left anterior descending coronary artery, [K+]o was increased, myocardial pH was decreased and MAPD was shortened. Glibenclamide completely abolished the shortening of MAPD, while partial elevation of [K+]o remained even in the presence of glibenclamide. This suggests that the shortening of MAPD is dependent mainly on the activation of K(ATP) channels. Both models in the present study demonstrate that different types of potassium channels are involved in the regulation of action potential duration.

References

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Citations

Jun 30, 2011·Europace : European Pacing, Arrhythmias, and Cardiac Electrophysiology : Journal of the Working Groups on Cardiac Pacing, Arrhythmias, and Cardiac Cellular Electrophysiology of the European Society of Cardiology·Scott A BernsteinGregory E Morley
Jun 28, 2005·Journal of Theoretical Biology·O V AslanidiA V Holden
Oct 23, 2012·American Journal of Physiology. Heart and Circulatory Physiology·Le GuiQing-Hui Chen
Dec 15, 2015·Physiological Reviews·Monique N Foster, William A Coetzee

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