Role of ANP in the Renal Proximal Tubule Mitochondrial Function in Type 1 DKD

Introduction: Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease. The proximal tubule (PT) is a key player in DKD development. Mitochondrial (mito) dysfunction and mito-induced oxidative stress in DKD are well-studied accelerators of tubular injury. The atrial natriuretic peptide (ANP) has been linked to mitochondrial reactive oxygen species (mitoROS) production and PT injury; however, the exact role of ANP in PT function in Type 1 DKD (T1DKD) has yet to be established. We hypothesize that in DKD, ANP is a beneficial factor that improves PT mitochondrial function via protection from oxidative stress-induced ferroptosis. Methods: T1DKD was induced by streptozotocin (STZ; 75mg/kg) in male and females ANP knock-out (SS NPPA-/- ) and wild-type (SS WT ) rats on the Dahl SS background at 9-10 weeks of age. Baseline, midpoint, and endpoint blood glucose, urine, and body weights were collected. Western blotting was done on isolated cortical tissue. Renal fibrosis was measured in PicroSirius Red and ferroptosis via Prussian Blue staining, analysis in FIJI after color deconvolution as area fraction. 1-way and 2-way ANOVA (Origin 2019b) were used for comparisons. Results: Male STZ- SS WT and STZ-SS NPPA-/- groups exhibited similar body weight (231.7 ± 14.8 vs. 230.9 ± 8.4 g, respectively), two-kidney weight to body weight ratio (31.8 ± 0.9 vs. 28.4 ± 1.5 mg/g), and endpoint hyperglycemia (with blood glucose levels >650 mg/dL). Female STZ-SS NPPA-/- vs. female STZ- SS WT displayed similar relationships for body weight, two-kidney weight to body weight ratio, endpoint hyperglycemia, and cortical fibrosis (p<0.5). Both male STZ- SS WT and STZ-SS NPPA-/- groups had high diuresis (59.9 ± 3.1 vs. 52.7 ± 3.2 mL/24hr/100gTBW) and a dramatic decline in renal function measured by GFR (0.05 ± 0.01 vs 0.10 ± 0.04 compared to corresponding vehicle-treated groups 0.3 ± 0.04 vs 0.3 ± 0.03 mL/min/2KW/TBW; respectively, p<0.05). Histological analysis revealed elevated cortical fibrosis (4.6 ± 0.2 vs. 3.1 ± 0.2 % area, respectively, p<0.05) and Prussian Blue staining (ferroptosis indicator; 1.4 ± 0.1 vs. 1.1 ± 0.04 % area, respectively, p<0.05) in male STZ-SS NPPA-/- compared to male STZ- SS WT . In the kidney cortex, STZ-SS NPPA-/- rats compared to STZ- SS WT rats exhibit a significant increase in OXPHOS complex V (2.5 ± 0.1 vs. 2.3 ± 0.03 a.u., respectively, p<0.05). Conclusion: Lack of ANP promotes DKD-related tubulointerstitial fibrosis, alterations in mitochondrial function, and ferroptosis related pathways. Pilot data showed that this relationship may also hold true for females. Future studies will provide mechanistic insight into the role of ANP in mito-related oxidative stress and assess the role of ANP in PT ferroptosis in detail. Funded by R01 DK126720, R01 DK129227, R01 HL148114, U54HL169191, TL1 DK139566. 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.