Mediates the electrogenic exchange of Ca2+ against Na+ ions across the cell membrane, and thereby contributes to the regulation of cytoplasmic Ca2+ levels and Ca2+-dependent cellular processes. Contributes to cellular Ca2+ homeostasis in excitable cells. Contributes to the rapid decrease of cytoplasmic Ca2+ levels back to baseline after neuronal activation, and thereby contributes to modulate synaptic plasticity, learning and memory. Plays a role in regulating urinary Ca2+ and Na+ excretion.