Abstract
Summary: Coronary arterio-venous K+ differences and cardiac rhythm were studied in 31 dogs under pentobarbital anaesthesia during and subsequent to occlusive constriction of the left anterior descending coronary artery for 10, 20 or 40 minutes. Ventricular fibrillation developed in nine animals during occlusion and in ten of the remaining 22 within seconds of release of constriction. In the absence of ventricular fibrillation, following release of coronary constriction positive, coronary arterio-venous K+ difference (0.60 ± 0.26 (SD) mEq/ litre; P < 0.001), indicating myocardial K+ uptake, was rapidly established in the ten experiments in which it was measured and persisted for several minutes in each of eight experiments. In two experiments positive was converted to negative difference by electrical induction of ventricular fibrillation. Myocardial K+ uptake was not found in five experiments when ventricular fibrillation intervened spontaneously within seconds of release of constriction, presumably because of the K+ depleting influence of ventricular fibrillation per se. The arterio-venous K+ difference then (–0 -56 ± 0.45 mEq/ litre) was significantly different (P< 0.001) from that which occurred in the absence of arrhythmia following reperfusion. While rapid cellular K+ exchange may be responsible for ventricular ectopic activity and subsequent fibrillation such an aetiological relation was not proven.
Published Version
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