Acid challenge to the esophageal mucosa: Effects on local nitric oxide formation and its relation to epithelial functions

To evaluate the effect of esophageal acid exposure on epithelial function, transmucosal potential, histopathological markers of acute tissue damage, and local nitric oxide production were examined in healthy volunteers treated with proton pump inhibitors ( group I), patients with treated reflux disease ( group II), and patients with untreated erosive reflux disease ( group III). The participants were randomized to esophageal perfusion with either saline or HCl. Denominators of acute acid exposure were balloon cells in superficial layers and superficial densification. The nitric oxide concentrations in groups I to III increased from < 1, 10.0 +/- 10.0, and 20.6 +/- 19.9 ppb, respectively, to 300 +/- 80, 1360 +/- 1080, and 920 +/- 700 ppb after HCl infusion ( P < 0.001). Inducible nitric oxide synthase was consistently expressed in the epithelium. Blood flow was lower among reflux patients but did not correlate with acid exposure or nitric oxide. Nitric oxide is formed following acid perfusion and predominantly in gastroesophageal reflux disease.