Kidney Week

Abstract: PO2148

Atrial Natriuretic Peptide Deficiency Alters Mitochondrial Bioenergetics in Dahl Salt-Sensitivity Rats

Session Information

• Mechanisms of Kidney and Vascular Disease
  October 22, 2020 | Location: On-Demand
  Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

• 1403 Hypertension and CVD: Mechanisms

Authors

• Domondon, Mark, Medical University of South Carolina, Charleston, SC, US, Charleston, South Carolina, United States

Mark Domondon,

• Sultanova, Regina F., Medical University of South Carolina, Charleston, SC, US, Charleston, South Carolina, United States

Regina F. Sultanova,

• Schibalski, Ryan, Medical University of South Carolina, Charleston, SC, US, Charleston, South Carolina, United States

Ryan Schibalski,

• Ilatovskaya, Daria, Medical University of South Carolina, Charleston, SC, US, Charleston, South Carolina, United States

Daria Ilatovskaya,

Background

In the heart and fat tissue, Atrial Natriuretic Peptide (ANP) is known to affect mitochondrial bioenergetics. However, little is known about the effects of ANP on mitochondria in the kidney, especially in the context of salt-sensitivity (SS). We hypothesized that in SS hypertension ANP deficiency causes renal mitochondrial dysfunction and contributes to end-organ damage.

Methods

Hypertension was induced in male SS^NPPA-/- (Nppa (encoding for ANP) knockout in Dahl SS background) and SS^WT (wild type Dahl SS) rats by a 21-day long high salt diet challenge (HS, 4% NaCl). Normal salt diet (NS, 0.4% NaCl) was given to age-matched control animals. A combination of in vivo techniques and studies on isolated renal mitochondria (seahorse respiration and spectrofluorimetry assays) were used to test the role of Nppa knockout in mitochondrial bioenergetics.

Results

SS^NPPA-/- rats exhibit exacerbated salt-sensitivity of blood pressure and kidney injury when challenged with a HS diet. In order to test mitochondrial function in this model, we measured membrane potential and levels of superoxide and H₂O₂ in renal cortical mitochondria. TMRM, Amplex Red and MCLA were used to detect membrane potential, H₂O₂ and superoxide, respectively. We report a decrease in mitochondrial membrane potential in the SS^NPPA-/- rats vs SS^WT (both on NS and HS diets), and an increase in mitochondrial H₂O₂ and superoxide levels in the same groups, indicative of leakage within the ETC. A Western analysis revealed that in SS^WT rats SOD2 levels are increased by a HS diet, while in SS^NPPA-/- animals its expression is suppressed. In addition, we observed activation of the antioxidant capacity in the SS^NPPA-/- rats vs SS^WT (on HS diet). SS^NPPA-/- rats exhibited a difference in MCU (mitochondrial calcium uniporter) activity when compared to SS^WT, implying an effect on mitochondrial calcium uptake. Interestingly, seahorse analysis revealed elevation of the oxygen consumption rate (OCR) in the knockout rats on HS, while in HS fed SS^WT rats OCR was reduced (vs NS).

Conclusion

Lack of circulating ANP results in changes of mitochondrial bioenergetics in the renal tissue via effects on calcium uptake, and alters respiratory chain activity leading to changes in ROS production. Further studies will advance the understanding of the mitochondria-mediated mechanisms affecting renal damage susceptibility in SS hypertension.

Funding

• NIDDK Support