Evidence for a magnesium- and ATP-dependent calcium extrusion pump in dog erythrocytes.

Abstract Intact dog erythrocytes, whose Ca 2+ permeability had been increased with A23187 still maintained intracellular Ca 2+ below electrochemical equilibrium indicating that they could extrude Ca 2+ . This extrusion required no Na + gradient but apparently depended on intracellular ATP and Mg 2+ suggesting that it was mediated by an ATP-fuelled Ca 2+ pump.