Kidney Week

Abstract: TH-PO0040

Hypercalcemia Promotes Salt-Sensitive Hypertension by Activating the Na-Cl Cotransporter Through the CaSR-WNK4-SPAK Pathway in Distal Convoluted Tubules

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Basic Research
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

• 1101 Fluid, Electrolyte, and Acid-Base Disorders: Basic

Authors

• Ariyoshi, Hiroaki, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Hiroaki Ariyoshi, MD

• Maeoka, Yujiro, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Yujiro Maeoka, MD, PhD

• Yakushiji, Ryo, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Ryo Yakushiji

• Harada, Wataru, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Wataru Harada, MD

• Yoshida, Maria, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Maria Yoshida, MD

• Ishiuchi, Naoki, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Naoki Ishiuchi, DrMed

• Osaki, Yosuke, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Yosuke Osaki, MD, PhD

• Okubo, Aiko, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Aiko Okubo, MD, PhD

• Sasaki, Kensuke, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Kensuke Sasaki, MD, PhD

• McCormick, James A., Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States

James A. McCormick, PhD

• Masaki, Takao, Department of Nephrology, Hiroshima University Hospital, Hiroshima, Japan

Takao Masaki, MD, PhD

Background

The Na⁺–Cl^- cotransporter (NCC) in the distal convoluted tubule (DCT) regulates blood pressure by promoting sodium reabsorption when phosphorylated and activated by the WNK4–SPAK pathway. Hypercalcemia is associated with hypertension, but the role of renal sodium handling remains incompletely understood. Luminal calcium-sensing receptor (CaSR) activation enhances NCC phosphorylation via the WNK4–SPAK pathway, whereas increased intracellular Ca²⁺ activates calcineurin, leading to NCC dephosphorylation. This study aimed to determine the net effect of hypercalcemia on NCC activity and its contribution to hypertension.

Methods

C57BL/6 mice were fed a normal-Ca²⁺(NCa, 0.4% Ca²⁺), high- Ca²⁺(HCa, 2.0% Ca²⁺, with calcium carbonate or gluconate), or dihydrotachysterol (DHT)-containing diet for 3 or 7 days. To assess salt-sensitive hypertension, mice were fed a high-salt (HS) diet alone or combined with HCa (HS/HCa), and blood pressure was measured by tail cuff. Ex vivo, kidney slices were treated with the calcineurin inhibitor tacrolimus (Tac) or the CaSR inhibitor NPS2143 under normal- or high-Ca²⁺ conditions. In vitro, HEK293 cells overexpressing CaSR, WNK4, and SPAK were used.

Results

Mice fed HCa or DHT-containing diets exhibited hypercalcemia, hypercalciuria, and increased NCC phosphorylation, independently of the accompanying anion. Phosphorylated NCC (pNCC) levels positively correlated with plasma [Ca²⁺], and urinary Na/Cr was decreased in HCa-fed mice. CaSR was abundantly expressed in the thick ascending limb and modestly expressed in the DCT in NCa-fed mice, whereas its signal was increased in the DCT in HCa-fed mice, consistent with increased pNCC and pSPAK. HS/HCa-fed mice showed higher blood pressure and lower urinary Na/Cr with increased pNCC than HS-fed mice, suggesting salt-sensitive hypertension associated with NCC activation. In kidney slices, NPS2143 blunted high-Ca²⁺-induced NCC and SPAK phosphorylation, whereas Tac further enhanced phosphorylation under high-Ca²⁺ conditions. Similar changes in SPAK phosphorylation were observed in vitro, suggesting activation of both kinase and phosphatase pathways, with the kinase pathway predominating in the DCT.

Conclusion

Hypercalcemia enhances NCC activity primarily through activation of the CaSR-WNK4–SPAK pathway, thereby contributing to hypertension.