Loss of quin 2 accompanies degranulation of mast cells

Stimulation of quin 2 loaded mast cells in the presence of 1 mM extracellular calcium produced a rapid and sustained increase in quin 2 fluorescence. This was accompanied by degranulation and the release of histamine. When Ca was replaced by EGTA or when Mn was present, a decrease in fluorescence accompanied degranulation. The increase in quin 2 fluorescence accompanying stimulation of mast cells appears to be due to the interaction of extracellular Ca with quin 2 associated with the secretory granule matrix released upon exocytosis.