Epithelial Na Channels: Function and Diversity

作者：Lawrence G. Palmer · 发表于：Annual Review of Physiology · 年份：1992 · DOI：10.1146/annurev.ph.54.030192.000411 · 被引用次数：193 · 研究领域：Ion Transport and Channel Regulation

Epithelial Na channels are transporters located in the apical membranes of certain epithelial cells. The major function of these channels is to permit the controlled entry of Na+ ions into the cells from the luminal or mucosal fluids (e.g. the urine, feces, sweat, or respiratory tract secretions). The channel activity helps to control the composition of the excreted fluids; a higher activity leads to increased reabsorption of Na. Regulation of the amount of Na excreted by the kidney is essential to the proper control of both the volume and salt content of the extracellular fluids. These channels are defined by their ability to conduct Na ions, their location on apical plasma membranes of epithelial cells, and by their sensitiv­ ity to pyrazine-based, K-sparing diuretics such as amiloride. Within this rather broad definition, several classes of channels has recently emerged. This review focuses on the biophysical and regulatory properties of these various channel types and is not intended to be a comprehensive treatment of the entire literature on this subject. A number of reviews regarding epithelial Na channels have been published recently, which cover various aspects of the channels and their regulation (12, 18, 46, 55-57, 62, 70, 79).