Calcium-permeable ion channels in the kidney

Calcium ions (Ca 2+ ) are crucial for a variety of cellular functions. The extracellular and intracellular Ca 2+ concentrations are thus tightly regulated to maintain Ca 2+ homeostasis. The kidney, one of the major organs of the excretory system, regulates Ca 2+ homeostasis by filtration and reabsorption. Approximately 60% of the Ca 2+ in plasma is filtered, and 99% of that is reabsorbed by the kidney tubules. Ca 2+ is also a critical signaling molecule in kidney development, in all kidney cellular functions, and in the emergence of kidney diseases. Recently, studies using genetic and molecular biological approaches have identified several Ca 2+ -permeable ion channel families as important regulators of Ca 2+ homeostasis in kidney. These ion channel families include transient receptor potential channels (TRP), voltage-gated calcium channels, and others. In this review, we provide a brief and systematic summary of the expression, function, and pathological contribution for each of these Ca 2+ -permeable ion channels. Moreover, we discuss their potential as future therapeutic targets.