NEPHRO OPINION

H⁺/K⁺-ATPase Pump

▪ H⁺/K⁺-ATPase is a proton pump that exchanges H⁺ for K⁺ across a cell membrane using ATP.

Main location

▪ Gastric parietal cells → apical/canalicular membrane

▪ Renal α-intercalated cells → apical membrane

Gastric H⁺/K⁺-ATPase

▪ Pumps H⁺ into gastric lumen

▪ Brings K⁺ into parietal cell

▪ Uses 1 ATP per exchange cycle

Reaction: H⁺ (cell → lumen) ⇄ K⁺ (lumen → cell)

▪ Responsible for the final step of gastric acid secretion.

Regulation

▪ Stimulated by: ▫ Acetylcholine → M3 ▫ Gastrin → CCK-B ▫ Histamine → H2

▪ Inhibited by: ▫ Proton-pump inhibitors (PPIs) → omeprazole, pantoprazole, esomeprazole, etc. ▫ PPIs irreversibly inhibit H⁺/K⁺-ATPase.

Renal H⁺/K⁺-ATPase

▪ Present mainly in α-intercalated cells of the collecting duct. ▪ Secretes H⁺ into urine and reabsorbs K⁺. ▪ Helps in acid–base regulation and K⁺ conservation.

High-yield:

Gastric H⁺/K⁺-ATPase = H⁺ secretion + K⁺ absorption → final common pathway of gastric acid secretion.