Transmucosal Potential Difference as an Index of Esophageal Mucosal Integrity

Abstract

All the epithelia lining the gastrointestinal (GI) tract, including that of the esophagus, exhibit a transmucosal electrical potential difference (PD). The luminal surface of the GI mucosa is indeed electrically negative when compared with the serosal one. Although it was initially felt that the body of the esophagus exhibits a PD near 0 or slightly positive, recent studies, using parenteral reference electrodes, have 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 in clinical settings, most probably due to the difficulties encountered during measurement of mucosal PD. Reliable techniques to measure esophageal PD simultaneously with esophageal pressure or mucosal pH are now available. Application of these recently developed methodologies showed that measurement of esophageal PD during either manometry or endoscopy 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 patients with microscopic reflux esophagitis, PD exhibits less negative values which are significantly correlated with the degree of the mucosal damage. Normalization of the altered PD after either medical or surgical treatment makes it an additional parameter to evaluate the effect of a given therapy.

Bile-induced Adenosine Triphosphate Depletion and Mucosal Damage During Reflux Esophagitis

“…The transmucosal potential difference maintained across the healthy mucosa is thought to be due to asymmetric ion pumping combined with resistance to the back-diffusion of the separated charge (23). A decreased transmucosal potential difference is indicative of a loss of mucosal integrity and also points to a disturbed mitochondrial energy turnover (24). The degree of impairment of the protective mucosal barrier may range from reversible permeability changes to complete transmural necrosis.…”

Electrical parameters and ion species for active transport in human esophageal stratified squamous epithelium and Barrett's specialized columnar epithelium

“…ESSE and BSCE differ not only structurally, as the names imply, but also functionally, and one marker of this functional difference is reflected by differences in their in vivo transmural electrical potential difference (PD). The in vivo PD for ESSE averages Ϫ15 Ϯ 5 mV and the in vivo PD for BSCE is typically greater than Ϫ25 mV (11,22,24,30,39). Since the PD, according to Ohm's law, is the product of current times (electrical) resistance, such differences in PD for ESSE and BSCE indicate that these epithelia have fundamental differences in ion transport and/or barrier properties.…”

Acid Challenge to the Human Esophageal Mucosa: Effects on Epithelial Architecture in Health and Disease

“…PD was recorded online on a Personal Computer (Power Macintosh 7100/80, Apple Computer Inc., Cupertino, CA, USA). Measurements were performed by estimating the charge difference between the reference probe of a pH glass electrode located 5 cm above the LES and a subcutaneous NaCl-perfused catheter which were connected to each other via a calomel electrode (22).…”