ABSTRACT
Potassium channels (K channels) form a remarkably diverse group of ion channel structures. They are found in both excitable and non-excitable cells along the phylogenesis. These membrane proteins maintain the negative resting membrane potential, restore the membrane potential following a depolarizing stimulus, regulate the firing frequencies, the transmitter release, and the neuroendocrine secretion, and modulate electrolyte homeostasis and cell volume. Although the role of K channels in the membrane potential was discovered in the 1950s (Hille, 1992), knowledge of the structure, function, and pharmacology of K channels has progressed slowly because of the lack of suitable ligands. Advances in a number of techniques such as electrophysiological recording, cDNA cloning, and purification of toxins have contributed to the discovery of a wide variety of K channels that differ in their physiological, biophysical, and pharmacological characteristics. The expression of many different K channel families in the nervous system is most likely at the root of the diverse functions of K channels.
