Potassium Channels in the Heart
Ionic currents over the plasma membrane through channels are the cornerstone of excitable cells. Human cardiomyocytes are excitable and continuously cycle between a depolarized and a repolarized state every second throughout human life, initiating and coordinating cardiac pump function. Ion channels selective for potassium (K+) critically participate in cellular repolarization and contribute to stabilizing the diastolic membrane potential, thus shaping the cardiac action potential. Four different subfamilies of potassium channels are present in the heart: small conductance, calcium-activated potassium channels (SK or KCa2), inwardly rectifying potassium channels (Kir), two-pore-domain potassium channels (K2P), and voltage-gated potassium channels (KV). In the present review, the structure and biophysical function of these cardiac potassium ion channels are reviewed. Moreover, rectification, inactivation, and current dependency on the extracellular potassium concentration are explained.
The helpful discussions with Dr. Kirstine Calloe are profoundly appreciated.
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The author declares that he has no conflict of interest.
All animal studies summarized and reviewed in this article were conducted based on international, national, and/or institutional guidelines for the care and use of animals.
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