Expression, localization, and functional properties of inwardly rectifying K channels in the kidney.

Inwardly rectifying K (K) channels are expressed in multiple organs and cell types and play critical roles in cellular function. Most notably, K channels are major determinants of the resting membrane potential and K homeostasis. The renal outer medullary K channel (K1.1) was the first renal K channel identified and cloned in the kidney over two decades ago. Since then, several additional members, including classical and ATP-regulated K family classes, have been identified to be expressed in the kidney and to contribute to renal ion transport. Although the ATP-regulated K channel class remains the most well known due to severe pathological phenotypes associated with their mutations, progress is being made in defining the properties, localization, and physiological functions of other renal K channels, including those localized to the basolateral epithelium. This review is primarily focused on the current knowledge of the expression and localization of renal K channels but will also briefly describe their proposed functions in the kidney.