The electrogenic Na/HCO3 cotransporter (symporter) is the major HCO3^- transporter of the renal proximal tubule (PiT), located at the basolateral membrane (BLM), and also plays a noteworthy role in Na⁺ reabsorption. HCO3 transporters are important for regulation of intracellular pH (pHi) in most cells and also thereby regulate blood pH. This electrogenic Na/HCO3 cotransporter is first discovered using perfused Ambystoma tigrinum (salamander) renal, proximal tubules. This novel cotransporter mediates the movement of one Na⁺ ion with several HCO3^- ions, making it electrogenic, is blocked by stilbene compounds, but does not depend on intra- or extracellular Cl^-. This and similar cotransporters have been found in a number of tissues and cell types.