The major lithium transporting proteins include the sodium-hydrogen exchanger (NHE), voltage-gated sodium channels and the epithelial sodium channel (ENaC). The NHE exchanger has been suggested to regulate lithium uptake at the apical region of the cell as its family member NHE1 transports lithium highly efficiently. Voltage-gated sodium channelsare proteins with specific structures that allow them to form a pore through which sodium ions can pass through. They are exclusive to sodium ions and block other molecules from passing through. ENaC channels play a role in maintaining lithium levels, as lithium is excreted by the kidneys and are then reabsorbed in renal tubules.