Ion channels

New explanations for old diseases

Ion channels are protein pores in the cell membrane that allow the passage of ions down their respective electrochemical gradients.1 The ubiquitous presence of ion channels among cells of unicellular and multicellular organisms suggests their importance in maintaining cellular integrity. Our understanding of the part that they play in disease has grown rapidly in the past few years, as a result of being able to explore the functional properties of ion channels in living cells.

Ion channels are classified broadly by the principal ion they carry (sodium, potassium, calcium, chloride) and the mechanisms by which they are opened and closed. Acetylcholine, for example, is a receptor specific agonist that acts at the postsynaptic membrane of the motor end plate to open chloride channels. Changes in membrane voltage or to concentrations of intracellular ions and molecules such as calcium and ATP can also open ion channels. The normal but unequal distribution of ions across the cell membrane can lead to the generation of a membrane potential as great as 100 mV.

Hodgkin and Huxley were the first to study ion channels, in 1952. …