NYMC Faculty Publications

Angiotensin II-Type-1a Receptor and Renal K+ Wasting During Overnight Low-Na+ Intake

Author Type(s)

Faculty

DOI

10.1681/ASN.0000000000000429

Journal Title

Journal of the American Society of Nephrology

First Page

1478

Last Page

1492

Document Type

Article

Publication Date

11-1-2024

Department

Pharmacology

Keywords

hypokalemia, ion transport, potassium (K) channels, renal function, renin angiotensin system

Disciplines

Medicine and Health Sciences

Abstract

Key PointsAngiotensin II-Type-1a-receptor in the distal convoluted tubule (DCT) plays a role in regulating sodium transport in the DCT.Angiotensin II-Type-1a-receptor in the DCT plays a role in maintaining potassium homeostasis during sodium restriction.BackgroundChronic angiotensin II perfusion stimulates Kir4.1/Kir5.1 of the distal convoluted tubule (DCT) via angiotensin II-Type-1a-receptor (AT1aR), and low-sodium intake also stimulates Kir4.1/Kir5.1. However, the role of AT1aR in mediating the effect of low salt on Kir4.1/Kir5.1 is not explored.MethodsWe used the patch-clamp technique to examine Kir4.1/Kir5.1 activity of the DCT, employed immunoblotting to examine Na-Cl cotransporter (NCC) expression/activity, and used the in vivo perfusion technique to measure renal Na+ and renal K+ excretion in control, kidney tubule-specific-AT1aR-knockout mice (Ks-AT1aR-KO) and DCT-specific-AT1aR-knockout mice (DCT-AT1aR-KO).ResultsAngiotensin II acutely stimulated the 40-pS-K+ channel (Kir4.1/Kir5.1-heterotetramer) and increased whole-cell Kir4.1/Kir5.1-mediated K+ currents and the negativity of DCT membrane potential only in late DCT2 but not in early DCT. Acute angiotensin II increased thiazide-induced renal Na+ excretion (ENa). The effect of angiotensin II on Kir4.1/Kir5.1 and hydrochlorothiazide-induced ENa was absent in Ks-AT1aR-KO mice. Overnight low-salt intake stimulated the expression of Agtr1a mRNA in DCT, increased whole-cell Kir4.1/Kir5.1-mediated K+ currents in late DCT, hyperpolarized late DCT membrane, augmented the expression of phosphor-Na-Cl-cotransporter, and enhanced thiazide-induced renal-ENa in the control mice. However, the effect of overnight low-salt intake on Kir4.1/Kir5.1 activity, DCT membrane potential, and NCC activity/expression was abolished in DCT-AT1aR-KO or Ks-AT1aR-KO mice. Overnight low-salt intake had no effect on baseline renal K+ excretion (EK) and plasma K+ concentrations in the control mice, but it increased baseline renal-EK and decreased plasma K+ concentrations in DCT-AT1aR-KO or in Ks-AT1aR-KO mice.ConclusionsAcute angiotensin II or overnight low-salt intake stimulated Kir4.1/Kir5.1 in late DCT, and AT1aR was responsible for acute angiotensin II or overnight low-salt intake-induced stimulation of Kir4.1/Kir5.1 and NCC. AT1aR of the DCT plays a role in maintaining adequate baseline renal-EK and plasma K+ concentrations during overnight low-salt intake.

Link to Full Text

Share

COinS