Morphological evidence of mast cell degranulation in an animal model of acid-induced esophageal mucosal injury.

In previous studies we have demonstrated that microvascular permeability increases early in the course of experimental acid-induced esophageal mucosal injury. This is associated with an increase in the intraluminal appearance of histamine, suggesting a possible role for mast cells in this form of injury. In the present study, quantitative analysis of esophageal mast cells was undertaken using both light and electron microscopy in opossums undergoing intraluminal esophageal acid perfusion or normal saline control perfusion. Light microscopy showed that animals perfused with either 50 or 100 mM hydrochloric acid had an approximate 50% decrease in the number of stainable esophageal mast cells. Stereologic analysis of electron micrographs revealed that within the mucosa, the mean area of the mast cells as well as nuclear area and area of intact granules were also significantly reduced in acid perfused animals. Taken together these quantitative morphological analyses suggest that intraluminal acid exposure is associated with degranulation and/or lysis of esophageal mast cells and that released mediators from esophageal mast cells may play a role in the pathophysiology of reflux esophagitis.