Interplay of potassium channel, gastric parietal cell and proton pump in gastrointestinal physiology, pathology and pharmacology

Author(s):  
Suchandra GOSWAMI
1996 ◽  
Vol 30 (12) ◽  
pp. 1425-1436 ◽  
Author(s):  
William R Garnett

OBJECTIVE: To summarize the published data on lansoprazole, a proton pump inhibitor approved by the Food and Drug Administration for use in the treatment of duodenal ulcer, erosive esophagitis, and pathologic hypersecretory conditions (e.g., Zollinger-Ellison syndrome). DATA SOURCES: Published data on lansoprazole identified by MEDLINE searches (1985–1996), as well as other pertinent literature. STUDY SELECTION: Clinical efficacy trials discussed were limited to multicenter, double-blind, parallel group, prospective studies, where possible. DATA SYNTHESIS: Lansoprazole inhibits gastric acid secretion via inhibition of gastric hydrogen/potassium adenosine triphosphatase (H+,K+-ATPase), an enzyme of the gastric parietal cell membrane that forms part of the proton pump that performs the final step in the acid secretory process. Lansoprazole binds covalently to parietal cell H+,K+-ATPase, rendering it nonfunctional and inhibiting the secretion of gastric acid. In clinical trials, lansoprazole has been shown to be more effective than placebo and standard doses of histamine (H)2-receptor antagonists and as effective as standard doses of omeprazole for the treatment of peptic ulcer disease, gastroesophageal reflux, Zollinger-Ellison syndrome, and nonsteroidal antiinflammatory drug—induced lesions. CONCLUSIONS: Lansoprazole is safe and effective for the treatment of acid-related disorders. It is more effective than the H2-receptor antagonists and comparable to omeprazole for these indications. The choice between lansoprazole and omeprazole is likely to be institution-specific and pharmacoeconomic.


2018 ◽  
Vol 315 (1) ◽  
pp. G36-G42 ◽  
Author(s):  
Alice Miriam Kitay ◽  
Marie-Therese Schneebacher ◽  
Anne Schmitt ◽  
Katharina Heschl ◽  
Sascha Kopic ◽  
...  

The H+,K+-ATPase was identified as the primary proton secretory pathway in the gastric parietal cell and is the pharmacological target of agents suppressing acid secretion. Recently, we identified a second acid secretory protein expressed in the parietal cell, the vacuolar H+-ATPase (V-type ATPase). The aim of the present study was to further characterize H+-ATPase activation by modulations in extracellular calcium via the calcium sensing receptor (CaSR). Isolated gastric glands were loaded with the pH indicator dye BCECF-AM [2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester] to measure intracellular pH. Experiments were conducted in the absence of sodium and potassium to monitor H+-ATPase-specific transport activity. CaSR was activated with the calcimimetic R568 (400 nM) and/or by modulations in extracellular Ca2+. Elevation in calcium concentrations increased proton extrusion from the gastric parietal cell. Allosteric modification of the CaSR via R568 and calcium increased vacuolar H+-ATPase activity significantly (ΔpH/minlowCa2+(0.1mM) = 0.001 ± 0.001, ΔpH/minnormalCa2+(1.0mM) = 0.033 ± 0.004, ΔpH/minhighCa2+(5.0mM) = 0.051 ± 0.005). Carbachol significantly suppressed calcium-induced gastric acid secretion via the H+-ATPase under sodium- and potassium-free conditions. We conclude that the V-type H+-ATPase is tightly linked to CaSR activation. We observed that proton pump inhibitor (PPI) exposure does not modulate H+-ATPase activity. This elevated blood calcium activation of the H+-ATPase could provide an explanation for recurrent reflux symptoms while taking a PPI therapy. NEW & NOTEWORTHY This study emphasizes the role of the H+-ATPase in acid secretion. We further demonstrate the modification of this proton excretion pathway by extracellular calcium and the activation of the calcium sensing receptor CaSR. The novelty of this paper is based on the modulation of the H+-ATPase via both extracellular Ca (activation) and the classical secretagogues histamine and carbachol (inactivation). Both activation and inactivation of this proton pump are independent of PPI modulation.


2017 ◽  
Vol 152 (5) ◽  
pp. S418
Author(s):  
Yuki Hirata ◽  
Shinji Fukuda ◽  
Kazuhiko Yamada ◽  
Kazuhide Higuchi ◽  
Yuki I. Kawamura ◽  
...  

2017 ◽  
Vol 116 (8) ◽  
pp. 613-619 ◽  
Author(s):  
Hung-Pin Lin ◽  
Yu-Hsueh Wu ◽  
Yi-Ping Wang ◽  
Yang-Che Wu ◽  
Julia Yu-Fong Chang ◽  
...  

Author(s):  
John G. Forte ◽  
Joseph G. Duman ◽  
Nimesh J. Pathak ◽  
Kent L. Mcdonald

1993 ◽  
Vol 71 (3) ◽  
pp. 191-200 ◽  
Author(s):  
JOHN M. PETTITT ◽  
BAN-HOCK TOH ◽  
JUDY M. CALLAGHAN ◽  
PAUL A. GLEESON ◽  
IAN R. VAN DRIEL

2001 ◽  
Vol 281 (2) ◽  
pp. C407-C417 ◽  
Author(s):  
David A. Ammar ◽  
Phuong N. B. Nguyen ◽  
John G. Forte

Acid secretion by the gastric parietal cell is controlled through movement of vesicles containing the proton pump, the H+-K+-ATPase (HK). We have used latrunculin B (Lat B), which binds to monomeric actin, to investigate actin turnover in the stimulated parietal cell. In isolated gastric glands, relatively high concentrations of Lat B were required to inhibit acid accumulation (ED50∼70 μM). Cultured parietal cells stimulated in the presence of low Lat B (0.1–1 μM) have reduced lamellipodia formation and some aberrant punctate phalloidin-stained structures, but translocation of HK and vacuolar swelling appeared unaffected. High Lat B (10–50 μM) resulted in gross changes in actin organization (punctate phalloidin-stained structures throughout the cell and nucleus) and reduced translocation of HK and vacuolar swelling. Resting parietal cells treated with high Lat B showed minor effects on morphology and F-actin staining. If resting cells treated with high Lat B were washed immediately before stimulation, they exhibited a normal stimulated morphology. These data suggest distinct pools of parietal cell actin: a pool highly susceptible to Lat B primarily involved in motile function of cultured cells; and a Lat B-resistant pool, most likely microvillar filaments, that is essential for secretion. Furthermore, the stimulation process appears to accentuate the effects of Lat B, most likely through Lat B binding to monomer actin liberated by the turnover of the motile actin filament pool.


Sign in / Sign up

Export Citation Format

Share Document