Salivary response to esophageal acid in normal subjects and patients with reflux esophagitis.

We studied the effect of esophageal acid perfusion on salivation in patients with reflux esophagitis and in normal subjects. Serial 10-min saliva collections were obtained by expectoration during perfusion of the esophagus with water, and then 0.1 N HCl (pH 1.2) for 50 min or 0.01 N HCl (pH 2.1) for 120 min. Within 1-5 min of beginning 0.1 N HCl perfusion, all 8 patients with esophagitis developed heartburn accompanied by an increase in saliva flow. By the time the severity of heartburn required discontinuation of HCl perfusion (10-40 min), saliva flow had increased nearly fourfold. With 0.1 N HCl perfusion, 8 of 10 volunteers developed mild heartburn after 22 +/- 3 min (mean +/- SE), whereas 0.01 N HCl induced heartburn in 6 of 10 volunteers after 57 +/- 12 min of perfusion. Saliva flow increased concurrently with the onset of heartburn and doubled in those volunteers who developed heartburn. Saliva flow did not change in those volunteers who were without heartburn. We conclude that esophageal acid perfusion unaccompanied by heartburn does not affect salivation. However, saliva flow increases concurrently with the onset of heartburn, a phenomenon called "water brash" when clinically evident. The increased saliva flow that accompanies heartburn may act as an endogenous antacid that serves as a protective response to symptomatic gastroesophageal reflux.