Ion channels in renal epithelia are involved in maintenance of the volume and ion composition of the epithelial cells themselves and of the entire organism. The latter function depends on transepithelial ion transport, a process that often involves ion channels at the apical (luminal) and/or the basolateral (contraluminal) cell membranes. Regulation of these channels is accomplished within many different time frames, each of which can involve different molecular mechanisms of regulation. Changes in membrane voltage, intracellular ion composition, or mechanical force on the membrane mediate short-term regulation. Biosynthesis, degradation, and reversible transfer of channels to or from cytoplasmic stores are responsible for longer term regulation. Covalent modification of channel proteins can be involved in either short- or long-term regulation. In this review we outline the different models of ion channel regulation in renal epithelia and give examples that emphasize the physiological roles of these channels in specific nephron segments.
