The energetic coupling of acid secretion in gastric mucosa

The relation between acid secretion and oxidative metabolism has been investigated using nondestructive optical techniques to monitor the redox level of respiratory chain components in the intact, isolated bull-frog gastric mucosa. High rates of acid secretion are found to be associated with cytochrome reduction while inhibition of secretion results in oxidation of the respiratory chain components. Changes in chloride secretion, independent of hydrogen ion secretion, result in opposite cytochrome redox changes indicating that the interaction with oxidative metabolism differs for the two secretory processes. Measurement of intracellular pH changes using indicator dyes shows a correlation between cytochrome reduction and increased pH. The results suggest that there exists a close coupling between the respiratory chain components and hydrogen ion secretion and that this coupling may involve changes in intracellular pH rather than changes in high energy phosphate compounds as previously suggested.