K depletion modifies the properties of Sch-28080-sensitive K-ATPase in rat collecting duct.
Two distinct Sch-28080-sensitive K-adenosine triphosphatases (K-ATPases) were previously described in the rat nephron: a ouabain-resistant K-ATPase (type I) present in collecting ducts (CD) and a ouabain-sensitive from (type II) located in proximal tubules (PT) and thick ascending limbs (TAL). In K-depleted rats, K-ATPase activity is increased in CD, whereas it is reduced in PT and TAL. Because expression of colonic H-K-ATPase is restricted to the CD of K-depleted rats, we hypothesized that K-ATPase from the CD of K-depleted rats might be different from types I and II. Indeed, type III K-ATPase displays higher sensitivities to ouabain and to Sch-28080 than type II, a lower sensitivity to Sch-28080 than type I, and, conversely to types I and II, it can be stimulated by Na+. Pharmacological differences between types II and III K-ATPases were confirmed by [3H]ouabain binding experiments. Thus the rat kidney expresses three K-ATPases that differ by their pharmacological and kinetic properties, their distribution profile along the nephron and their behavior during K depletion.
Buffin-Meyer
B
B
Laboratoire de Biologie Intégrée des Cellules Rénales, Commissariat à l'Energie Atomique, Saclay, France.
Younes-Ibrahim
M
M
Barlet-Bas
C
C
Cheval
L
L
Marsy
S
S
Doucet
A
A
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D017506:H(+)-K(+)-Exchanging ATPase; D007093:Imidazoles / Q000494:pharmacology*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D009399:Nephrons / Q000378:metabolism; D010042:Ouabain / Q000378:metabolism / Q000494:pharmacology; D011191:Potassium Deficiency / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000494:pharmacology; D014018:Tissue Distribution
D027682:Cation Transport Proteins; D004791:Enzyme Inhibitors; D007093:Imidazoles; C035235:Sch 28080; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; C022761:potassium transporting ATPase; D017506:H(+)-K(+)-Exchanging ATPase