Renal β-intercalated cells maintain body fluid and electrolyte balance.
Inactivation of the B1 proton pump subunit (ATP6V1B1) in intercalated cells (ICs) leads to type I distal renal tubular acidosis (dRTA), a disease associated with salt- and potassium-losing nephropathy. Here we show that mice deficient in ATP6V1B1 (Atp6v1b1-/- mice) displayed renal loss of NaCl, K+, and water, causing hypovolemia, hypokalemia, and polyuria. We demonstrated that NaCl loss originated from the cortical collecting duct, where activity of both the epithelial sodium channel (ENaC) and the pendrin/Na(+)-driven chloride/bicarbonate exchanger (pendrin/NDCBE) transport system was impaired. ENaC was appropriately increased in the medullary collecting duct, suggesting a localized inhibition in the cortex. We detected high urinary prostaglandin E2 (PGE2) and ATP levels in Atp6v1b1-/- mice. Inhibition of PGE2 synthesis in vivo restored ENaC protein levels specifically in the cortex. It also normalized protein levels of the large conductance calcium-activated potassium channel and the water channel aquaporin 2, and improved polyuria and hypokalemia in mutant mice. Furthermore, pharmacological inactivation of the proton pump in β-ICs induced release of PGE2 through activation of calcium-coupled purinergic receptors. In the present study, we identified ATP-triggered PGE2 paracrine signaling originating from β-ICs as a mechanism in the development of the hydroelectrolytic imbalance associated with dRTA. Our data indicate that in addition to principal cells, ICs are also critical in maintaining sodium balance and, hence, normal vascular volume and blood pressure.
Victor
V
Gueutin
Marion
M
Vallet
Maximilien
M
Jayat
Janos
J
Peti-Peterdi
Nicolas
N
Cornière
Françoise
F
Leviel
Fabien
F
Sohet
Carsten A
CA
Wagner
Dominique
D
Eladari
Régine
R
Chambrey
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051399:Aquaporin 2 / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D053503:Epithelial Sodium Channels / Q000378:metabolism; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000166:cytology / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019899:Paracrine Communication; D017419:Potassium, Dietary / Q000097:blood*; D012982:Sodium, Dietary / Q000097:blood*; D025262:Vacuolar Proton-Translocating ATPases / Q000172:deficiency / Q000235:genetics; D014882:Water-Electrolyte Balance
C496024:Aqp2 protein, mouse; D051399:Aquaporin 2; C530995:BKCa protein, mouse; D053503:Epithelial Sodium Channels; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D017419:Potassium, Dietary; D012982:Sodium, Dietary; D000255:Adenosine Triphosphate; C480628:Atp6v1b1 protein, mouse; D025262:Vacuolar Proton-Translocating ATPases; D015232:Dinoprostone