Figure 7.

Schematic overview of sarcolemmal transporters that regulate Na⁺_i concentration in cardiac myocytes. At steady-state Na⁺ influx is exactly balanced by Na⁺ efflux and consequently Na⁺_i concentration remains unchanged. Na⁺ enters the cells through electroneutral transporters, such as the NKCC, NHE-1, and NBCn. The Na⁺-dependent acid extruders are stimulated by a continuous H⁺ supply via the Cl⁻-dependent acid loaders CHE and AE. Moreover, the electrogenic pathways through which Na⁺ enters is by NBCe, forward mode NCX and Na⁺ channels. The total Na⁺ influx is balanced by electrogenic Na⁺ extrusion mainly via the Na/K-pump and a minor part by reverse mode NCX.