Publisher Summary This chapter deals with regulation of chloride-dependent and independent bicarbonate transporters. Regulation of acid–base homeostasis as well as other ionic concentrations, such as Na+, is critical for animal life. Vertebrates, mammals in particular, generate significant amounts of acid via metabolism; these organisms must excrete acid (H+) or increase systemic HCO3ˉ concentration to buffer this metabolic acid. Bicarbonate, along with CO2, is the major pH buffering system of biological fluids. The chapter also defines the modes of membrane anion transport. Membranes present a barrier to the movement of ions and other solutes. The cell membrane is a mosaic of phospholipids, cholesterol and proteins. The phospholipids make the bulk of the membrane and form a bilayer. This lipid bilayer has the hydrophilic phosphate and sugar head-groups facing both the outside world and the inside world.