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Abstract: FR-PO528

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

Session Information

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
  • Zietara, Adrian P., University of South Florida, Tampa, Florida, United States
  • Dissanayake, Lashodya Vindana, University of South Florida, Tampa, Florida, United States
  • Kravtsova, Olha, University of South Florida, Tampa, Florida, United States
  • Staruschenko, Alexander, University of South Florida, Tampa, Florida, United States
Background

The role of renal inwardly-rectifying potassium (Kir) 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 Kir5.1) 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 Kir5.1 in Dahl salt-sensitive rats (SSKcnj16-/- ).

Methods

To evaluate the baseline acid-base status of SSKcnj16-/- rats, 12-week-old male SSWT and SSKcnj16-/- 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, SSKcnj16-/- rats showed significantly lower blood pH and HCO3-, but higher urinary NH4+, titratable acid and NAE than SSWT 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 SSKcnj16-/- rats. For NH4+ transport, increased mRNA expression of Rhbg and Rhcg may indicate enhanced NH4+ excretion in the kidney of SSKcnj16-/- 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 Kir5.1 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