A comparison of membrane enzymes of human and pig oesophagus; the pig oesophagus is a good model for studies of the gullet in man.

The distribution and relative catalytic activities of five plasma membrane enzymes (alkaline phosphatase, dipeptidyl peptidase IV, gamma-glutamyl transpeptidase, microsomal alanyl aminopeptidase and glutamyl aminopeptidase) were examined in human and pig oesophagus. In both species, alkaline phosphatase activity occurred in basal and suprabasal cells of the epithelium and in capillaries. Stromal cells in the human submucosa were particularly reactive. Dipeptidyl peptidase IV was present in blood vessels and capillaries in man and pig and in submucous glands in the pig. The enzyme was also present in both species in the lamina propria cells immediately adjacent to the epithelial basal lamina. In the human, gamma-glutamyl transpeptidase occurred in the epithelial basal cells and in isolated basal and lower prickle cells in the pig. Stromal cells in the human submucosa were strongly reactive and capillaries in the muscularis propria in both species moderately active. Microsomal alanyl aminopeptidase was detected in lamina propria cells adjacent to the epithelial basal cell layer in man and pig and at the apices of mucous cells in pig submucous glands. Weak glutamyl aminopeptidase activity was confined to capillaries in both species. The findings of this study, along with the ready availability of pig oesophagus, suggest that the pig may be a suitable model for studies of the gullet in man.