Extracellular potassium accumulation in acute myocardial ischemia.

In acute reversible myocardial ischemia extracellular potassium activity rises 4 to 5 fold within 10 to 15 min after interruption of coronary perfusion. The underlying net cellular K+ loss is likely to be caused by an increased K+ efflux in the presence of maintained Na+/K+ pumping (i.e. active K+ influx). A hypothesis is discussed which relates increased K+ efflux to the formation of weak acids in the cells during anaerobic metabolism. However, the exact mechanism remains to be determined by further experimental investigations.