FUNCTION OF CHLORIDE CHANNELS IN THE KIDNEY

Numerous Cl⁻ channels have been identified in the kidney using physiological approaches and thus are thought to be involved in a range of physiological processes, including vectorial transepithelial Cl⁻ transport, cell volume regulation, and vesicular acidification. In addition, expression of genes from several Cl⁻ channel gene families has also been observed. However, the molecular characteristics of a number of Cl⁻ channels within the kidney are still unknown, and the physiological roles of Cl⁻ channels identified by molecular means remain to be determined. A gene knockout approach using mice might shed further light on the characteristics of these various Cl⁻ channels. In addition, study of diseases involving Cl⁻ channels (channelopathies) might clarify the physiological role of specific Cl⁻ channels. To date, more is known about CLC Cl⁻ channels than any other Cl⁻ channels within the kidney. This review focuses on the physiological roles of CLC Cl⁻ channels within the kidney, particularly kidney-specific ClC-K Cl⁻ channels, as well as the recently identified maxi anion channel in macula densa, which is involved in tubulo-glomerular feedback.