Renal potassium channels: Function, regulation, and structure

Many transport functions in renal tubules depend on potassium (K) channels. Not only does K secretion and the maintenance of external K balance depend on K channel activity in principal tubule cells, but K channels also regul ate cell volume, they are an integral party of cell function in all tubule cells because of their key role in the generation of the cell-negative elec trical7 potential that affects the transmembrane movement of many charged s olutes. Moreover, the recycling of K across the apical membrane of the thic k ascending limb (TAL) plays an important role in the control of NaCl reabs orption in this tubule segment. Significant progress in our understanding o f the structure and function of renal K channels has become possible by com bining several strategies. These include transport studies in single tubule s, application of the patch-clamp technique for exploring the properties of single K channels in native tubules and the cloning, and expression of div erse K channels of renal origin. Insights from these investigations promise to provide a deeper understanding of the mechanism by which K channels par ticipate in many diverse tubule functions.