Potassium efflux in heart muscle during activity: extracellular accumulation and its implications.

作者：Richard Kline, Martin Morad · 发表于：The Journal of Physiology · 年份：1978 · DOI：10.1113/jphysiol.1978.sp012400 · 被引用次数：114 · 研究领域：Electrochemical Analysis and Applications、Ion channel regulation and function、Cardiac electrophysiology and arrhythmias

1. Extracellular K+ activity and transmembrane potential were simultaneously monitored with a K+-selective micro-electrode placed in the extracellular space and a standard KCl-filled micro-electrode in the intracellular space of the frog ventricular muscle. 2. K+ was found to accumulate during activity and had the approximate magnitude and time course to account for the measured membrane depolarization. 3. The magnitude of the K+ accumulation depended on the frequency of stimulation, diameter of the muscle and temperature of the bathing solution. 4. The time constants of accumulation and decay were dependent only on the diameter and the temperature of the strip. A Q10 of 2 was measured for the decay of accumulated K+. 5. Double barrelled K+-electrodes were used to monitor the change in K+ activity accompanying a single action potential, since the reference barrel allowed for rapid compensation of the electrical potential fluctuations encountered in the subendothelial space. 6. K+ accumulated continuously during the plateau to a level which increased external K concentration by about 1 mM. This increase in the subendothelial space corresponds to about 1-3 muA/cm2 or 10-30 pmole/cm2-sec-1 of net K+ efflux. These values are at least an order of magnitude larger than required to discharge the membrane capacitance. 7. There is no direct relation between action potential duration and rate of development or magnitude of K+ accumulation during that action potential. 8. Increase in th...