The sodium-calcium exchanger is a membrane protein with anti-activity activity with the function of removing calcium from cells in favor of sodium.
The exchanger does not use energy to exchange the ions, but uses the sodium gradient to allow the calcium to be extruded from the cell and poured into the extracellular liquid, allowing extracellular sodium to enter the cell: in particular removes a calcium ion in favor of three sodium ions.
However, the exchanger can reverse its direction and therefore enter the calcium if the sodium concentration inside the cell increases. This is used, in particular situations, to increase the inotropic effect of the heart. In particular, going to inhibit the activity of the Na + / K + pump (which extrudes three sodium ions for two potassium) we have an increase in intracellular sodium concentration and hence a reversal of the exchanger activity and a rise in calcium cytoplasmic within myocardial cells.
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