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action current[′ak·shən ‚kə·rənt]
in physiology, the electric current that develops in nerve and muscle cells and in some plant cells between their excited areas and adjacent resting areas. It is caused by changes in the ionic permeability of the cell membrane and in potential that occur in the excited areas, and is recorded by extracellular electrodes. Action current plays an important role in the distribution of action potential along a cell or fiber.