Interrelationship between esophageal challenge with mechanical and chemical stimuli and salivary protective mechanisms.

Using our newly developed model of esophageal perfusion in humans, we were able to study the esophagosalivary reflex in 20 healthy volunteers (12M, 8F; mean age 40 yr). The placement of the intraesophageal catheter resulted in a 6.3-fold increase in the salivation rate over the baseline value (2.27 +/- 0.28 vs. 0.36 +/- 0.06 ml/min; p = 0.02), whereas inflation of the catheter balloons evoked a 6.9-fold increase (2.52 +/- 0.21; p < 0.001) in the rate of salivation. A stepwise and significant decline of salivation (p = 0.02), observed during subsequent perfusion with NaCl was prevented when perfusion with HCl and HCl/pepsin solutions was implemented. The placement of the intraesophageal catheter resulted in a significant increase of salivary pH over its basal value (7.77 +/- 0.05 vs. 6.89 +/- 0.11; p < 0.001). A gradual decline of salivary pH during subsequent perfusion with NaCl was eliminated when saline was replaced with HCl or HCl/pepsin (7.76 +/- 0.04 vs. 7.46 +/- 0.09; p < 0.01). Intraesophageal tubing enormously potentiated the viscosity of saliva (44.50 +/- 9.0 vs. 9.3 +/- 1.0 mPa.s; p < 0.001). A subsequent decline of viscosity during continuous perfusion with saline was also prevented when HCl was substituted for NaCl (29.95 +/- 4.5 vs. 19.50 +/- 3.30; p < 0.05). A significant potentiation of salivary volume, viscosity, and pH during esophageal stimulation of mechano- and chemoreceptors may suggest a contributing role of the esophagosalivary reflex in the maintenance of the esophageal mucosal integrity under the impact gastroesophageal reflux.