Active Ion Transport

in biology, the migration of ions (sodium, potassium, magnesium, calcium, and others) in living systems through various cellular membranes (for example, nerve and muscle cells, erythrocytes, and others) against a concentration gradient, solubility gradient, electroosmotic gradient, or other gradients, using the energy of metabolic processes accumulated in the system of adenosinephosphoric acids (primarily adenosine triphosphate) and other macroenergetic—that is, energy-rich—compounds. The decay of one molecule of adenosine triphosphate is usually accompanied by transport of two or three nonvalent cations or one bivalent cation. The primary enzyme responsible for converting energy into work that transports ions is adenosine triphosphate, which is concentrated in biological membranes and is activated by the presence of sodium, potassium, and magnesium ions and lipides. One particular case of this enzyme’s action is the energy supply for active ion transport (primarily of sodium ions) through nerve cell membranes.