Kidney Week

Abstract: FR-PO528

Deletion of Kcnj16 Disturbs Acid-Base Homeostasis in Dahl Salt-Sensitive Rats

Session Information

• Fluid, Electrolyte, Acid-Base Disorders: Basic
  November 03, 2023 | Location: Exhibit Hall, Pennsylvania 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

• Xu, Biyang, University of South Florida, Tampa, Florida, United States

Biyang Xu,

• Zietara, Adrian P., University of South Florida, Tampa, Florida, United States

Adrian P. Zietara,

• Dissanayake, Lashodya Vindana, University of South Florida, Tampa, Florida, United States

Lashodya Vindana Dissanayake,

• Kravtsova, Olha, University of South Florida, Tampa, Florida, United States

Olha Kravtsova,

• Staruschenko, Alexander, University of South Florida, Tampa, Florida, United States

Alexander Staruschenko,

Background

The role of renal inwardly-rectifying potassium (K_ir) channels in regulating acid-base homeostasis has been suggested by various studies. Previous studies demonstrated that patients with loss-of-function variants of Kcnj16 (the gene encoding K_ir5.1) presented with disturbed acid-base homeostasis. However, the underlying mechanisms are still not fully understood. Here, we aim to investigate the renal handling of acid-base balance under the deletion of K_ir5.1 in Dahl salt-sensitive rats (SS^Kcnj16-/- ).

Methods

To evaluate the baseline acid-base status of SS^Kcnj16-/- rats, 12-week-old male SS^WT and SS^Kcnj16-/- rats were used (N=5 per group). 24 hrs urine and blood were collected for measurement of blood pH, HCO3^- and urinary pH, NH4⁺, titratable acid, and net acid excretion (NAE). At the end of the experiments, RNA-Seq and Western blot analysis were performed on extracted kidneys to evaluate the expression of key transporters related to renal HCO3^-, H⁺, and NH4⁺ handling.

Results

At baseline, SS^Kcnj16-/- rats showed significantly lower blood pH and HCO3^-, but higher urinary NH4⁺, titratable acid and NAE than SS^WT rats. RNA-Seq and Western blot analysis revealed altered expression of several transporters essential for renal handling of HCO3^-, H⁺ and NH4⁺. For example, for HCO3^- transport, both RNA-seq and Western blot analysis demonstrated increased expression of NBCe1 while decreased expression of pendrin, which may suggest enhanced HCO3^- reabsorption in the proximal tubule while inhibited HCO3^- excretion in the collecting duct of SS^Kcnj16-/- rats. For NH4⁺ transport, increased mRNA expression of Rhbg and Rhcg may indicate enhanced NH4⁺ excretion in the kidney of SS^Kcnj16-/- rats. For H⁺ transport, elevated mRNA and protein expression of NHE3 may suggest enhanced H⁺ secretion in the proximal tubule. Additionally, although the RNA-Seq suggested increased expression of various subunits of V-ATPase, we didn’t observe any differences at protein levels.

Conclusion

Our data suggested that at baseline, loss of K_ir5.1 initiated metabolic acidosis and altered the renal transport of HCO3^-, NH4⁺, and H⁺ in Dahl SS Rats. The following analysis will further investigate the phenotype after the NH₄Cl challenge test in both genders.

Funding

• Other NIH Support