Background: Primary cilia regulation of renal function and blood pressure (BP) in health and disease is incompletely understood. The current study investigated the effect of nephron ciliary loss on renal physiology, blood pressure and ensuing cystogenesis.
Methods: Mice underwent doxycycline (DOX)-inducible nephron-specific knockout (KO) of the Ift88 gene at 2 months of age using a Cre-LoxP strategy. Blood pressure, kidney function, and renal pathology were studied 2 and 9 months after DOX (Ift88 KO) or vehicle (control).
Results: At 2 months post DOX, male, but not female, Ift88 KO, compared to sex-matched control, mice had reduced BP, enhanced salt-induced natriuresis, increased urinary nitrite/nitrate (NOx) excretion, and increased kidney NOS3 levels which localized to the outer medulla; the reductions in BP in male mice were prevented by L-NAME. At 9 months post DOX, male, but not female, Ift88 KO mice had polycystic kidneys, elevated BP and reduced urinary NOx excretion. No differences were observed in plasma renin concentration, plasma aldosterone, urine vasopressin or urine PGE2 between Ift88 KO and control mice at 2 or 9 months post DOX.
Conclusions: Nephron cilia disruption in male, but not female, mice: 1) reduces BP prior to cyst formation; 2) increases NOx production that may account for the lower BP prior to cyst formation; and 3) induces polycystic kidneys that are associated with hypertension and reduced renal NO production.