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

Atrial and brain natriuretic peptides activate GC-A/NPRA (guanylyl cyclase-A/natriuretic peptide receptor-A) and regulate blood pressure and electrolyte homeostasis. Renal tubule (RT) dysfunction results in decreased kidney function and increased blood pressure. We determined the sex-specific consequences of RT cell-specific deletion of Npr1 (encoding NPRA) on blood pressure and renal hemodynamics.

Mice were generated with inducible RT knockout by breeding lox-flanked (flox/flox: f/f) exons 1 to 2 in Npr1 with mice expressing the Pax8-rtTA-LC-1-Cre transgene. Doxycycline-treated RT cell-specific Npr1 knockout (Npr1 f/-), heterozygous (HT; Npr1 f/+), and wild-type (Npr1 f/f) male and female mice were used. Proximal tubule, distal tubule, and cortical collecting duct were isolated from RT-Npr1 knockout mice and did not express Npr1 mRNA or protein.

RT cell-specific male knockout and HT mice showed significantly lower glomerular filtration rate, creatinine clearance, and urinary sodium excretion than female mice, compared with wild-type mice. The effect of Npr1 deletion was more severe on high-salt diets than their normal-diet counterparts. Loss of Npr1 in RT segments significantly increased systolic blood pressure and mean arterial pressure in a sex-specific manner. Mutant male mice showed higher total urinary protein and albumin-creatinine ratios than female mice. On a high-salt diet, male knockout and HT mice showed greater salt sensitivity than female mice.

Loss of Npr1 along the nephron tubules leads to arterial hypertension and abnormal renal functional hemodynamic changes that are more pronounced in male mice compared with female mice.