ion channel

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i·on chan·nel

a specific macromolecular protein pathway, with an aqueous "pore," which traverses the lipid bilayer of a cell's plasma membrane and maintains or modulates the electrical potential across this barrier by allowing the controlled influx or exit of small inorganic ions such as Na+, K+, Cl-, and Ca2+. It plays an important role in propagation of the action potential in neurons, but also may control transduction of extracellular signals and contraction in muscle cells. In general, ion channels are characterized by their selectivity for certain ions, their specific regulation or gating of these ions, and their specific sensitivity to toxins.

ion channel

n.
A pathway through a protein molecule or complex in a cell membrane that modulates the electrical potential across the membrane by controlling the passage of small inorganic ions into and out of the cell.

ion channel

A protein that spans the lipid bilayer of the cell membrane and regulates the movement of charged particles (e.g., electrolytes) into and out of cells.
See also: channel

ion

an atom or group of atoms having a positive (cation) or negative (anion) electric charge by virtue of having gained or lost one or more electrons. Substances forming ions are electrolytes.

ion channel
see channel.
dipolar ion
zwitterion.
hydrogen ion
the positively charged hydrogen atom (H+), present to excess in acid solutions.
ion pair
the pair of ions created when an atom has had an electron removed by ionizing radiation.
ion pump
see calcium pump, sodium pump.
ion trapping
a strategy for treatment of poisonings based on the principle that cell membranes are less permeable to ionized compounds. With knowledge of the characteristics of the toxin, treatment can be given to alter the acid-base balance in favor of ionization.