ABSTRACT
Maintenance of a stable intracellular pH is central to cell metabolic processes and therefore for life itself. Regulation of intracellular [Hþ] involves active transport processes, modulation of production and utilization of organic acids, and chemical buffering. Characterization of these regulatory processes is extremely difficult because of the complex nature of the intracellular environment and remains a work in progress. Historically, most attempts at assessment of intracellular [Hþ] have been based on the assumption that the interior of the cell is a uniform solution. In fact, the interior milieu is extremely heterogeneous, containing vesicles, mitochondria, and multiple other structures that are known to create microenvironments in the cell with varying pH values (Fig. 1). In addition, cells differ widely in their metabolic and transport characteristics and therefore have differences in the nature of their acid-base homeostasis. Despite these shortcomings, extensive information has been acquired about cell pH and its regulation. This chapter reviews this information, covering both pH measurements and the nature of the transporters that regulate intracellular [Hþ] at the cell membrane and within its interior microenvironments.
