Introduction

Studies examining the regulation of intracellular pH (pHi) in vertebrate red blood cells can be generally divided into two research areas. Because blood is relatively easy to obtain and handle in a laboratory setting, it is an ideal tissue for studies of ion-transport processes in vertebrate membranes. Many investigators have therefore used red blood cells as a model tissue for in vitro studies to elucidate the ion-transport mechanisms involved in pHi regulation in vertebrates. The fact that different phylogenetic groups of vertebrates possess red blood cells with quite different membrane characteristics has led to a proliferation of this research and to the detailed description of a variety of ion-transport mechanisms that are involved in the transport of acid–base equivalents across vertebrate membranes. In contrast, other studies in this area have been oriented towards understanding the functional significance of the factors affecting red blood cell pH in vertebrates. Vertebrate red blood cells have a central role in the transport of O2 and CO2 between the tissues and respiratory surfaces. Since their pH and the carriage of these respiratory gases in blood are intimately related via the Bohr/Haldane and Root effects, the factors determining red blood cell pH in vertebrates have also been intensely studied by respiratory physiologists, whose main goal is to understand the mechanisms involved in the respiratory physiology of different vertebrate groups at both the cellular and organismal levels. Clearly, important insights into the subject of pH regulation in vertebrate red blood cells may be derived from research in each of these areas.