Direct demonstration of increased intracellular concentration of free calcium as measured by quin-2 in stimulated rat peritoneal mast cell.

Abstract

Rat mast cells, passively sensitized with monoclonal mouse IgE antibody, were stimulated with multivalent antigen, and an increase in cytoplasmic Ca2+ was determined by using the fluorescent probe quin-2. The increase in quin-2 fluorescence reached maximum within 20 sec after the antigen challenge and then gradually declined. A substantial increase in quin-2 fluorescence was observed in the presence of EGTA, indicating that bridging of cell-bound IgE antibody molecules by antigen induced not only Ca2' influx but also mobilization of intracellular Ca2+. Phosphatidylserine added to the medium enhanced both the antigen-induced histamine release and the increase in quin-2 fluorescence and slowed the rate at which the quin-2 signal returned to basal levels. Both the antigen-induced increase in quin-2 fluorescence and histamine release were inhibited by pretreatment of mast cells with inhibitors of methyltransferases, theophylline, or cromoglycate. It was also found that methyltransferase inhibitors and theophylline inhibited not only stimulus-dependent calcium influx but also release of bound calcium from intracellular stores. Other secretagogues, compound 48/80 (1 pg/ml) and Ca ionophore A23187 (0.1 /uM), induced a rapid increase in cytoplasmic Ca2+ in rat mast cells and subsequent histamine release. In contrast, the cocarcinogenic compound phorbol 12-myristate 13-acetate caused histamine release without increasing the quin-2 fluorescence.

Divalent cation dependence of the inhibition by phenothiazines of mediator release from mast cells

“…Its utility lies in the ease with which it may be isolated and by virtue of the fact that it responds to a wide array of stimuli . Studies with radiolabelled calcium (Foreman et al, 1977) and the fluorescent intracellular calcium probe quin 2 (Beaven et al, 1984;White et al, 1984) suggest that a cytosolic increase in calcium is the central event leading to exocytosis. Secretagogues promote entry of the cation into the cytosol either by increasing the permeability of the cell membrane to calcium (immunological and pharmacological ligands), mobilizing intracellular stores of the cation (polybasic Once in the cell, the mechanism by which the cation exerts its effects is unknown.…”

Apomorphine‐induced inhibition of histamine release in rat peritoneal mast cells

“…ATP is a secretagogue increasing the permeability of the mast cell membrane to ions without inducing loss of intracellular proteins (Cockroft & Gomperts, 1979a). TPA, the known activator of protein kinase C (Nishizuka, 1984), has the unique property of eliciting histamine release without increasing the free cytosol calcium concentration (White et al, 1984). To this list of specific mast cell activators, melittin has been added as an example of a secretagogue producing a gross alteration of the mast cell membrane and loss of lactate dehydrogenase (Pearce & Clements, 1982).…”

Synergistic effects of calcium‐mobilizing agents and adenosine on histamine release from rat peritoneal mast cells

“…The release is generally thought to be intimately related to an elevation of free cytosolic calcium (Foreman, 1980) which increases upon IgEreceptor stimulation (White et al, 1984). This increase of free intracellular calcium levels appears to be mediated by generation of inositol-trisphosphate (Beaven et al, 1984;Nakamura & Ui, 1985).…”