Renal Tubule Cell-Specific Npr1 is Essential to Regulate Blood Pressure and Kidney Dysfunction

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Molecular Endocrinology

Background:

• Atrial and brain natriuretic peptides are key regulators of blood pressure and electrolyte balance via GC-A/NPRA signaling.
• Renal tubule dysfunction is linked to impaired kidney function and hypertension.
• The sex-specific roles of NPRA in renal tubules remain incompletely understood.

Purpose of the Study:

• To investigate the sex-specific effects of deleting the gene for NPRA (Npr1) in renal tubule cells on blood pressure and renal hemodynamics.
• To determine how Npr1 deletion in renal tubules impacts kidney function and salt sensitivity.

Main Methods:

• Generated inducible renal tubule-specific Npr1 knockout mice using a Pax8-rtTA-Cre system and doxycycline treatment.
• Utilized Npr1 knockout (f/-), heterozygous (f/+), and wild-type (f/f) male and female mice on normal and high-salt diets.
• Confirmed Npr1 mRNA and protein absence in isolated proximal tubules, distal tubules, and cortical collecting ducts of knockout mice.

Main Results:

• Male knockout and heterozygous mice exhibited significantly reduced glomerular filtration rate, creatinine clearance, and urinary sodium excretion compared to females.
• Loss of Npr1 in renal tubules led to a sex-specific increase in systolic and mean arterial pressure, exacerbated by high-salt diets.
• Male mutant mice showed increased urinary protein and albumin-creatinine ratios, indicating greater renal damage and salt sensitivity.

Conclusions:

• Renal tubule Npr1 deletion causes arterial hypertension and abnormal renal hemodynamics.
• These detrimental effects are significantly more pronounced in male mice than in female mice.
• Targeting NPRA signaling in renal tubules may offer sex-specific therapeutic strategies for hypertension.