Na/K-ATPase signaling tonically inhibits sodium reabsorption in the renal proximal tubule.
FASEB J
; 37(4): e22835, 2023 04.
Article
em En
| MEDLINE
| ID: mdl-36856735
ABSTRACT
Through its classic ATP-dependent ion-pumping function, basolateral Na/K-ATPase (NKA) generates the Na+ gradient that drives apical Na+ reabsorption in the renal proximal tubule (RPT), primarily through the Na+ /H+ exchanger (NHE3). Accordingly, activation of NKA-mediated ion transport decreases natriuresis through activation of basolateral (NKA) and apical (NHE3) Na+ reabsorption. In contrast, activation of the more recently discovered NKA signaling function triggers cellular redistribution of RPT NKA and NHE3 and decreases Na+ reabsorption. We used gene targeting to test the respective contributions of NKA signaling and ion pumping to the overall regulation of RPT Na+ reabsorption. Knockdown of RPT NKA in cells and mice increased membrane NHE3 and Na+ /HCO3 - cotransporter (NBCe1A). Urine output and absolute Na+ excretion decreased by 65%, driven by increased RPT Na+ reabsorption (as indicated by decreased lithium clearance and unchanged glomerular filtration rate), and accompanied by elevated blood pressure. This hyper reabsorptive phenotype was rescued upon crossing with RPT NHE3-/- mice, confirming the importance of NKA/NHE3 coupling. Hence, NKA signaling exerts a tonic inhibition on Na+ reabsorption by regulating key apical and basolateral Na+ transporters. This action, lifted upon NKA genetic suppression, tonically counteracts NKA's ATP-driven function of basolateral Na+ reabsorption. Strikingly, NKA signaling is not only physiologically relevant but it also appears to be functionally dominant over NKA ion pumping in the control of RPT reabsorption.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Túbulos Renais
Limite:
Animals
Idioma:
En
Revista:
FASEB J
Assunto da revista:
BIOLOGIA
/
FISIOLOGIA
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Estados Unidos