Abstract
In order to elucidate the localization of an anti-allergic agent, Tranilast, in mast cells, light and electron microscopic radioautographies (LMRAG and EMRAG) were performed. The mast cells collected from rat peritoneal cavity were incubated for 0 to 60 min in a medium containing 3H-labeled Tranilast. After incubation, they were fixed, embedded in epoxy resin and processed for LMRAG and EMRAG. In LMRAG, the radioautographic silver grains were frequently localized over and around the cytoplasmic granules and their number increased according to the prolongation of incubation time. In EMRAG, many silver grains were localized over the specific granules, especially on the perigranular membranes. From these results, it was demonstrated that Tranilast was rapidly taken into the cytoplasm of mast cells and that the specific localization of this agent on pengranular membranes and/or their adjoining structures might participate in the inhibition of degranulation of mast cells.
