Role of ClC-K and barttin in low potassium-induced sodium chloride cotransporter activation and hypertension in mouse kidney.

The sodium chloride cotransporter (NCC) has been identified as a key molecule regulating potassium balance. The mechanisms of NCC regulation during low extracellular potassium concentrations have been studied in vitro. These studies have shown that hyperpolarization increased chloride efflux, leading to the activation of chloride-sensitive with-no-lysine kinase (WNK) kinases and their downstream molecules, including STE20/SPS1-related proline/alanine-rich kinase and NCC. However, this mechanism was not studied in vivo Previously, we developed the barttin hypomorphic mouse (Bsnd mice), expressing very low levels of barttin and ClC-K channels, because barttin is an essential β-subunit of ClC-K. In contrast with Bsnd mice, Bsnd mice survived to adulthood. In Bsnd mice, and NCC activation after consuming a low-potassium diet was clearly impaired compared with that in wild-type (WT) mice. In ex vivo kidney slice experiment, the increase in pNCC and duanyu1842K in low-potassium medium was also impaired in Bsnd mice. Furthermore, increased blood pressure was observed in WT mice fed a high-salt and low-potassium diet, which was not evident in Bsnd mice. Thus, our study provides in vivo evidence that, in response to a low-potassium diet, ClC-K and barttin play important roles in the activation of the cascade and blood pressure regulation. © 2018 The Author(s).

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