Uptake, Storage and Release of Histamine by Rat Peritoneal Mast Cells in vitro

Rat peritoneal mast cells, when incubated in histamine‐H 3 containing medium, were shown to take up and concentrate histamine. The uptake was proportional to incubation time and to extracellular histamine concentration. Metabolic inhibitors did not significantly affect the uptake. The exogenous histamine was bound to mast cell granules in about the same proportion as found for the endogenous. Treatment of mast cells with compound 48/80 released the same relative amounts of both exogenous and endogenous histamine. These results suggest that histamine was taken up by passive diffusion and stored in the mast cell granules. High concentrations of 5‐HT inhibited the histamine uptake, whereas histidine and 5‐HTP did not influence the process.