In vitro uptake of 5-hydroxytryptamine and dopamine by rat mast cells after exocytosis induced by antigen or compound 48/80.

Mast cells from the peritoneal and pleural cavities of actively sensitized rats were isolated and incubated with biogenic amines (5-hydroxytryptamine and dopamine) with or without pretreatment with specific antigen. An anaphylactic reaction resulting in the release of 20-25% of the histamine in the cells led to a slightly reduced amine uptake. At concentrations which induced histamine release comparable to that during the anaphylactic reaction compound 48/80 had a similar effect on the uptake of the two amines. Histamine release induced by higher concentrations of compound 48/80 led to a more pronounced reduction in the uptake of the amines, the reduction being roughly proportional to the extent of the histamine release. It is concluded that the reduction in the in vitro amine uptake after anaphylactic and compound 48/80-induced histamine release is due to the fact that there are a fewer intact granules capable of storing histamine and not primarily due to a damage to the mechanisms by which mast cells take up biogenic amines in vitro. The observations further strengthen the view that anaphylactic and compound 48/80-induced histamine release are non-cytolytic processes.