Rat mast cells and bone marrow-derived mouse mast cells (BMMC) were sensitized with mouse IgE mAb, and permeabilized by ATP to introduce guanosine-5'-O-(3-thiotriphosphate) (GTPγS) and/or guanosine-5'-O-(2-thiodiphosphate) (GDPβS) into the cells. After ATP-induced lesions were resealed with Mg2+, the cells were challenged by Ag to determine the effect of the nonhydrolyzable guanosine phosphate on Ag-induced hydrolysis of phosphoinositides and histamine release. Introduction of GTPγS into permeabilized rat mast cells or BMMC, followed by exposure of the cells to extracellular Ca2+, resulted in histamine release, but failed to induce hydrolysis of phosphoinositides. It was also found that introduction of GTPγS into the cells did not synergistically enhance Ag-induced histamine release. Introduction of GDPβS into sensitized BMMC inhibited the GTPγS-dependent, Ca2+-induced histamine release but failed to inhibit Ag-induced histamine release. The results suggest that GTPγS-dependent, Ca2+-induced histamine release and Ag-induced histamine release go through independent biochemical pathways. It was also found that introduction of GTPγS or GDPβS into sensitized BMMC neither enhanced nor inhibited Ag-induced formation of inositol phosphates. These results together with previous findings that pretreatment of BMMC with either pertussis toxin or cholera toxin does not affect Ag-induced hydrolysis or phosphoinositides, indicate that a G protein is involved in the transduction of IgE-mediated triggering signals to phospholipase C in rodent mast cells.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Immunology|
|Publication status||Published - 1989|
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