505 Impaired Esophageal Mucosa Integrity in Refractory Reflux Disease Patients on Proton Pump Inhibitors. A Role for Residual Acid Reflux?

Abstract

was assayed by immunoprecipitation and western blotting. To further investigate if PAR2 activation sensitized acid-induced ATP release through TRPV1 and ASICs, pretreatment with IRTX or amiloride for 45 min before trypsin (4 mg/ml, 60 min) was administered. Results: Acid stimulated the release of ATP from HEEC (217 ± 58 % Control, P<0.0001). This was reduced by 60% after pretreatment with IRTX (P<0.0001) and by 79% after amiloride pretreatment (P<0.0001). TRPV1 siRNA transfection also decreased acid-induced ATP release (54%, P<0.01). Pretreatment of HEECs with trypsin, tryptase or the PAR-2 agonist further increased acid-induced ATP release (Table). Trypsin or tryptase led to the phosphorylation of TRPV1, indicating TRPV1 sensitization. Acid-induced ATP release sensitized by trypsin was partially blocked by IRTX and amiloride (39% and 50%, respectively, P<0.0001). Conclusions: Acid-induced ATP release was augmented by TRPV1 and ASICs through PAR2 activation. These findings suggest that the pathophysiology of heartburn sensation or esophageal hypersensitivity may be associated with the activation of PAR-2, TRPV1 and ASICs. Effects of trypsin, tryptase or PAR-2 agonist on acid-induced ATP release in HEEC