Disorders in ion channels have been linked to many types of epilepsy. Now researchers have discovered a mechanism that regulates how sodium and potassium ion channels collaborate in the sending of electrical signals in the brain. It is possible that disruption of this mechanism may be an underlying cause of epilepsy.

Sodium and potassium ions are tiny particles with an electric charge, present throughout the body in every cell and in the fluid surrounding every cell. Using channels in their outer membrane, cells pump extra potassium to their insides, or pump extra sodium outside. Nerve cells send signals using this mechanism. When enough message input has been received by the cell, the sodium channels open, and sodium ions are released into the cell again; because they carry a charge, their movement creates an electrical signal. This signal is sent on through the nerve cell when the potassium channels open, allowing potassium ions to flow out of the cell.

Professor Edward Cooper and his colleagues at the University of Pennsylvania School of Medicine showed that sodium and potassium channels were anchored to nerve cells' surfaces in a similar manner. Chemical tests showed that an almost identical molecular chain links each channel to a protein called ankyrin-G, which in turn binds strongly to the cell surface. The similarity of the link ensures the channels work in partnership, thus controlling the timing and pattern of nerve signals.

The researchers, whose work was published in March in the Journal of Neuroscience, also investigated this mechanism in other species. They found that the ankyrin-G link is present in all vertebrate species, such as fish, birds and mammals, but is lacking in invertebrates, such as insects and shellfish. The partnership of these channels may be essential for the higher abilities of vertebrate brains.

A better understanding of this interaction between channels may help develop new treatments for various conditions, including the types of epilepsy already known to be channelopathies, and some that have not yet been linked to ion channels.

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