Elusive role of the Na-K-2C1 cotransporter in the choroid plexus

摘要

In all cells and tissues that have been studied, the Na-K-2C1 cotransporter (NKCC1) is believed to mediate inward transport of Na~+, K~+, and Cl~ ions (2). However, two recent papers published in Nature Medicine (9) and Nature Communication (18) argued for unconventional outward NKCC1 transport in choroid plexus. A paper in this issue of American Journal of Physiology-Cell Physiology challenges this view and supports the conventional inward transport (5). Can both sides of the argument be right? Why is this dispute difficult to resolve? Are assumptions or measurements in one or the other camp erroneous? We will attempt to answer these questions in this Viewpoint article.