Effects of age on gastric alkaline and nonparietal fluid secretion in humans

Little is known about the effect of age on gastric alkaline and nonparietal secretion. Using a previously validated technique, we prospectively measured gastric HCO₃^- and nonparietal volume secretion, as well as secretion of H⁺, Na⁺, K⁺, and Cl^-, in 114 healthy human beings over a wide age range (18-82 years). Each subject had normal oxyntic mucosal histology, was on no medication known to affect gastric secretion, and was studied under both basal (fasting) conditions and following stimulation of gastric H⁺ secretion by pentagastrin. There was a significant (p < 0.05) decline in gastric HCO₃^-, Na⁺, and nonparietal fluid secretion with advancing age, but not in H⁺, K⁺, Cl^- or parietal fluid secretion. As a consequence of reduced gastric HCO₃^- and nonparietal fluid secretion, mean H⁺ concentrations in gastric juice increased significantly with advancing age. Thus, in healthy subjects with normal gastric histology, advancing age was associated with a significant decline in gastric HCO₃^-, Na⁺, and nonparietal fluid secretion, resulting in an increase in gastric acidity (H⁺ concentration).