Intercalated cells-specific ClC-K2 deletion ameliorates Ang II-induced hypertension by compromising renal Cl ^- conservation

Background: Hypertension affects over 50% of the adult US population. The renal collecting duct (CD) is responsible for the fine tuning of NaCl excretion and setting salt sensitivity. It is accepted that inability to downregulate ENaC activity/expression during high-sodium intake leads to excessive Na + conservation resulting in the development of salt-sensitive hypertension. Previously, we showed that ENaC blockade in principal cells of CD reduces Angiotensin II (Ang II)-induced hypertension. However, accumulated evidence also suggests a crucial role for dietary chloride in blood pressure regulation. ClC-K2, a Cl - -permeable channel expressed on the basolateral side of several distal nephron segments including intercalated cells (ICs) of the CD. Loss-of-function mutations in ClC-K2 cause Bartter’s syndrome type 3, which is associated with urinary salt wasting and hypotension. While hypotensive phenotype of Bartter’s syndrome type 3 was thought to be attributed to the impaired NaCl reabsorption in thick ascending limb and distal convoluted tubule, little is known about the role of ClC-K2 in intercalated cells of renal collecting duct in regulation of blood pressure. Methods: Here, we utilized two transgenic ClC-K2 knockout mouse models using cre-loxP: a renal nephron-specific knockout (RN-KO) and an ICs-specific knockout (IC-KO) generated using Pax8 Cre and V-ATPase B1 Cre, respectively. To test the role of ClC-K2 in the regulation of salt-sensitive blood pressure, we used subcutaneous osmotic pumps with Ang II (400ng/min kgBW), dietary NaCl restrictions, immunofluorescent microscopy (IFM), systemic measurements, and patch clamp technique. Results: IC-specific deletion of ClC-K2 significantly blunted the hypertensive effect of chronic Ang II infusion, although this effect was considerably smaller than that observed in RN-KO mice. We next investigated whether the decreased Cl - reabsorption in the CD is responsible for the observed resistance to Ang II infusion in IC-KO mice. Indeed, dietary NaCl and Cl - restrictions led to significantly elevated urinary Cl - wasting, when compared to the genetic controls. Importantly, dietary NaCl, and Cl - , but not Na + deficiencies induced moderate but significant hypotension in IC-KO mice. IFM analysis revealed diminished pendrin levels and compromised apical translocation in IC-KO mice on a baseline and in response to dietary NaCl restrictions. At the same time, IC-KO mice had augmented ENaC activity and expression on the baseline pointing the compensated response. In contrast to control animals, NaCl dietary restrictions did not further elevate ENaC expression in IC-KO mice. Conclusions: In summary, we demonstrate that ClC-K2 in intercalated cells of the renal collecting duct is crucial for regulation of salt-sensitive blood pressure by contributing to the development of Ang II-induced hypertension and Cl - conservation. This research was supported by NIDDK DK117865, DK136462, AHA 20EIA35260097 (to O. Pochynyuk), AHA 24POST1191738 (to A. Atamanchuk) and AHA 24SCEFIA1259812 (to K. Pyrshev). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.