Internal and external K super(+) help gate the inward rectifier

Recent investigations have demonstrated substantial reductions in internal (K super(+)) in cardiac Purkinje fibers during myocardial ischemia. The authors investigated the possible role these changes in internal K super(+) might play in abnormal electrical activity by studying the effects of both internal and external (K super(+)) on the gating of the inward rectifier iK sub(1) in isolated Purkinje myocytes with the whole-cell patch-clamp technique. The changes suggest an important role of internal K super(+) in gating iK sub(1) and may contribute to changes in the electrical properties of the myocardium that occur during ischemia.