Podocyte Cell-Specific Guanylyl Cyclase/Natriuretic Peptide Receptor-A is Required for Blood Pressure and Renal Hemodynamics in Sex-Specific Manner
Abstract Body: The cardiac hormones atrial and brain natriuretic peptides (ANP and BNP) bind to guanylyl cyclase-A/natriuretic peptide receptor-A (GC-A/NPRA) that increases intracellular production of cGMP and stimulates natriuresis, diuresis, and vasorelaxant activities, thereby, reduces blood pressure (BP) and fluid volume. The role of ANP/NPRA signaling in podocytes, highly specialized epithelial cells covering the outer surfaces of renal glomerular capillaries, remains unclear. The objective of this study was to determine the effect of conditional deletion of podocyte (PD)-specific Npr1 (encoding GC-A/NPRA) in gene-knockout (KO) male and female mice in a sex-dependent manner. Tamoxifen-treated wild-type control (PD Npr1 f/f; WT), heterozygous (PD-Cre-Npr1 f/+; HT), and gene-knockout (PD-Cre-Npr1 f/-; KO) mice were fed a normal-, low-, or high-salt diet for 4 weeks. Podocytes isolated from HT and KO male and female mice showed complete absence of Npr1 mRNA and NPRA protein compared to WT mice. On a normal-salt diet the mean arterial pressure (MAP) and heart rate (HT) were significantly greater in both male and female PD-Npr1 KO mice compared with WT mice as measured by radiotelemetry method. On a high-salt diet, the systolic blood pressure (SBP) was significantly higher (p<0.01; p<0.001) in the PD-Npr1 HT mice (male:108.8 ± 1.10; female: 97 ± 0.80) and KO mice (male:114.60 ± 1; female: 100.10 ± 1.10) compared with WT mice (male: 100.60 ± 0.80; female: 93.30 ± 0.80) at 4 weeks. On normal-, low-, and high-salt diets, plasma creatinine, and urinary protein were significantly increased (p<0.05; p<0.01; p<0.001), while plasma total protein and albumin were significantly reduced (p<0.05; p<0.01; p<0.001) in the Npr1 HT and KO male and female mice compared to WT mice. These changes were significantly greater in males than females. On a normal-salt diet, the glomerular filtration rate (GFR) was significantly (p<0.05; p<0.01; p<0.001) decreased in PD Npr1 HT mice (male: 0.67 ± 0.06; female: 0.81 ± 0.09) and KO mice (male:0.46 ± 0.04; female: 0.69 ± 0.05) compared with WT mice (male:1.1 ± 0.07; female: 1.2 ± 0.1). These observations suggest that in podocyte, ANP/NPRA/cGMP signaling may be crucial in the maintenance and regulation of GFR and hypertension and point as a biomarker of BP and renal hemodynamics in a sex-dependent manner.
Ramasamy, Chandramohan
( Tulane University Health Sciences Center
, New Orleans
, Louisiana
, United States
)
Neelamegam, Kandasamy
( Tulane University Health Sciences Center
, New Orleans
, Louisiana
, United States
)
Ramachandran, Samivel
( Tulane University Health Sciences Center
, New Orleans
, Louisiana
, United States
)
Pandey, Kailash
( Tulane University Health Sciences Center
, New Orleans
, Louisiana
, United States
)
Author Disclosures:
Chandramohan Ramasamy:No Answer
| Kandasamy Neelamegam:No Answer
| Samivel Ramachandran:No Answer
| Kailash Pandey:DO NOT have relevant financial relationships