TRANSMUCOSAL POTENTIAL DIFFERENCE AS AN INDEX OF ESOPHAGEAL MUCOSAL INTEGRITY

All the epithelia lining the gastrointestinal (GI) tract, including th at of the esophagus, exhibit a transmucosal electrical potential diffe rence (PD). The luminal surface of the GI mucosa is indeed electricall y negative when compared with the serosal one. Although it was initial ly felt that the body of the esophagus exhibits a PD near 0 or slightl y positive, recent studies, using parenteral reference electrodes, hav e shown a negative PD of around - 15 mV. Measurement of esophageal PD has been mainly used to locate both the lower and the upper esophageal sphincters but very rarely to evaluate esophageal mucosal integrity i n clinical settings, most probably due to the difficulties encountered during measurement of mucosal PD. Reliable techniques to measure esop hageal PD simultaneously with esophageal pressure or mucosal pH are no w available. Application of these recently developed methodologies sho wed that measurement of esophageal PD during either manometry or endos copy provides meaningful information about mucosal integrity. Indeed, tissue injury, either neoplastic or inflammatory, usually results in a less negative PD. In contrast, an abnormally high negative PD is very often observed in patients with columnar-lined lower esophagus. In pa tients with microscopic reflux esophagitis, PD exhibits less negative values which are significantly correlated with the degree of the mucos al damage. Normalization of the altered PD after either medical or sur gical treatment makes it an additional parameter to evaluate the effec t of a given therapy.