Effect of heat stress on rabbit esophageal epithelium.

Hot beverages expose the esophageal epithelium to temperatures as high as 58 degrees C. To study the impact of such temperatures, rabbit esophageal epithelium was exposed to luminal heat or both luminal and serosal heat while mounted in Ussing chambers. Luminal heat, mimicking exposure to hot beverages, reduced potential difference (PD) and resistance (R) when applied at >/=49 degrees C and reduced short-circuit current (Isc) at >/=60 degrees C. At >/=60 degrees C, subepithelial blisters developed. Higher temperatures reduced R only moderately and reversibly. In contrast, the Isc declined sharply and irreversibly once threshold was reached. Luminal and serosal heat also reduced PD, Isc, and R, although the threshold for reduction in Isc was now similar to that for R. Additionally, luminal and serosal heat reduced Isc more than R for any given temperature and resulted in blisters at lower temperatures (50 degrees C) than luminal heat alone. The heat-induced decline in Isc was attributed in part to inactivation of Na-K-ATPase activity, although other transport systems could have been equally affected, and the decline in R to an increase in paracellular permeability. The latter effect on R also contributed to an increase in tissue sensitivity to luminal acid damage. Consumption of hot beverages exposes the esophagus to temperatures that can negatively impact epithelial structure and function. Impaired barrier function by heat increases the risk of esophageal damage by subsequent contact with (refluxed) gastric acid. These findings help explain in part the association between esophageal disease and consumption of hot beverages.