Thrombin-induced degranulation of cultured bone marrow-derived mast cells: effect on calcium uptake.
The role of calcium in the mechanism of thrombin activation of bone marrow-derived mast cells (BMMC) was explored by measuring the changes in the uptake of 45Ca2+ into quiescent BMMC and into cells stimulated by thrombin or by IgE-antigen. The results indicate that activation of BMMC by either thrombin or IgE-antigen is Ca2+-dependent. One million BMMC, activated by 0.05-5 U thrombin, accumulated 45Ca2+ in a concentration-dependent manner, which levelled off at around 1 U thrombin. Extracellular 45Ca2+ uptake of thrombin-stimulated cells is saturable within 90 seconds and corresponds to the kinetics of histamine release, whereas that of IgE-antigen exposed cells continues unabated for over 5 min. The pattern of 45Ca2+ uptake of IgE-sensitized BMMC exposed to thrombin suggests that the pro-stimulatory locus of thrombin action on the surface membrane is distinct from that of IgE.
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D000818:Animals; D001854:Bone Marrow Cells; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006596:Hexosaminidases / Q000378:metabolism; D006636:Histamine Release / Q000187:drug effects*; D007073:Immunoglobulin E / Q000276:immunology; D007700:Kinetics; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D013917:Thrombin / Q000494:pharmacology*
D007073:Immunoglobulin E; D006596:Hexosaminidases; D013917:Thrombin; D002118:Calcium