Active transport and ATP in frog gastric mucosa

Gastric H/K⁺-ATPase

“…Since no candidates for this type of pump were found, the research evolved to the ques tion of whether the high concentration of mi tochondria would only serve as a source for ATP and whether gastric acid secretion would be driven by an H+-transporting ATPase. It was shown that ATP can indeed act as a direct and onlv source of energy in the parietal cell [16].…”

Immunoelectron microscopic investigation of glutathione-peroxidase in the rat stomach.

“…The gastric parietal cell maintains a steep ionic gradient as it secretes HCl and must tolerate a high hydrogen ion concentration and ionic gradients are highly vulnerable to intracellular superoxide anion concentrations (2). Recently, Thaete et al (19) reported that superoxide dismutase, an enzyme that catalyzes the dismutation of superoxide anion as a toxic free radical, was predominantly localized in the gastric parietal cells of the rats by immunohistochernical investigations.…”

Gastric Mucosal Energy Metabolism in Stress Ulcer

“…This anaerobic metabolism in the glandular mucosa o f rats is more effective in the antral portion than that taking place in the corpus mucosa; lactate 1-dehydrogenase (anaerobic isoenzyme) predominates in the antrum, while lactate 5-dehydrogenase (aerobic isoenzyme) predominates in the corpus [23], One may speculate, based on these data, the increase incidence o f ulcerative lesions in the cor pus versus those in the antral mucosa. The relationship between HC1 secretion and ATP levels in gastric mucosa was studied by Durbin and coworkers [8], who pointed out high ATP levels in frog's gastric mucosa at rest. M ozsik and Vizi [18] showed a correlation between the increase in HC1 secretion and the drop in ATP and ADP levels in gastric mucosa of pylorus-ligated rats, but reported significant high con centrations of stomach wall ATP in a group of pylorus-ligated and vagotomized rats [19], These changes have been related to inverse variations o f gastric Mg2+-Na+-K+-dependent ATPase, an enzyme localized in gastric microsomal fractions which has been implicated as a direct participant in the HC1 secretory process [10].…”