Neuronal Potassium Channels

Potassium (K) channels are proteins which span the membrane of cells and which, when open, allow the selective flow of K ions from one side of the membrane to the other (usually from the inside of the cell to the outside). They can be gated by a variety of stimuli including voltage, changes in intracellular calcium and certain other physiological mediators. In neurons, they have a number of functional roles related, primarily, to the electrical properties of the membrane. As such, they determine the neuronal action potential frequency, shape the neuronal action potential waveform and control the strength of synaptic contacts between neurons. Additionally, certain K channels regulate the absolute excitability of neurons and set (or contribute to) the neuronal resting membrane potential. Their physiological importance has been exemplified by the observations that mutations in K channel sequences in particular individuals leads to such varied clinical disorders as epilepsy, episodic ataxia, unregulated insulin secretion and deafness.