Histamine methyltransferase in dispersed cells from rabbit fundic mucosa.

The cellular distribution of histamine N-methyltransferase was studied in rabbit gastric mucosa. The fundic mucosa was dispersed by collagenase treatment in Hanks' or calcium-free medium. In calcium-free medium, the number of dispersed cells/g wet tissue, as well as their viability was increased; histamine N-methyltransferase recovery was up to three-fold larger than in cells prepared in Hanks' medium. Furthermore, the calcium-free medium led to a greater acid secretory response, whereas the cellular pepsinogen content tended to be lower. Histamine N-methyltransferase activity was found in all cell fractions but was higher in the larger cell types. The enzyme activity showed only a partial correlation with either oxyntic or chief cells. These results indicate that the use of calcium-free medium to disperse and isolate rabbit mucosal cells improves cell quality. Histamine N-methyltransferase in the rabbit fundic mucosa, is found in more than one cell type, primarily the oxyntic and chief cells.