The renal nephron consists of a series of distinct cell types which function in concert to maintain fluid and electrolyte balance and blood pressure. The renin angiotensin system (RAS) is central to sodium and volume balance. We aimed to determine how loss of angiotensin II signaling in the proximal tubule (PT), which reabsorbs the bulk of filtered sodium and volume, impacts solute transport throughout the nephron. We hypothesized that proximal tubule (PT) RAS disruption would not only depress PT sodium transporters, but also impact downstream Na+ transporters. Utilizing a mouse model in which the type 1a angiotensin receptor (AT1aR) is deleted specifically within the PT (AT1aR PTKO), we profiled the abundance of sodium transporters, channels, and claudins along the nephron. Absence of PT AT1aR signaling was associated with lower abundance of PT transporters (NHE3, NBCe2 and claudin 2) as well as lower abundance of downstream transporters (total and phosphorylated NKCC2, medullary Na,K-ATPase, phosphorylated NCC and claudin 7) versus controls. However, transport activities of NKCC2 and NCC (assessed with diuretics) were similar between groups in order to maintain electrolyte balance. Together, these results demonstrate the primary impact of angiotensin II regulation on sodium reabsorption in PT at baseline and the associated influence on downstream Na+ transporters, highlighting the ability of the nephron to integrate sodium transport along the nephron to maintain homeostasis.
S1928 Phosphorylation Tunes Vascular L‐type Channel Ca
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1.2 and Arterial Function during Angiotensin II Signaling and Hypertension
