title: Effects of calcium and phosphatidyl serine in rat mast cell reaction to dextran.
abstract: Histamine release from Sprague-Dawley rat mast cells by dextran was completely inhibited by the absence of exogenous Ca2+ (in contrast to release from the same cells by antigen). Also, spontaneous leakage of histamine from the cells increased in the absence of Ca2+, and cell responsiveness was not completely restored by readding Ca2+. We found no effective substitute for Ca2+ in the release reaction. Ca2+ was not maximally effective immediately when added back to Ca-deficient cells, but almost the full effect of diluting Ca2+ in the medium (which decreased release) and of adding PS (which increased release) were very rapidly established, suggesting that both Ca2+ and PS might act (in part) at superficial cell sites. Release from activated cells could be stopped short by adding glucose or by diluting the cell-dextran mixture with normal buffer, as well as by adding EDTA, which deserves further study.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent / Q000494:pharmacology; D003470:Culture Media; D003911:Dextrans / Q000494:pharmacology*; D004347:Drug Interactions; D004492:Edetic Acid / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D006636:Histamine Release / Q000187:drug effects*; D008297:Male; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
chemical_list: D002413:Cations, Divalent; D003470:Culture Media; D003911:Dextrans; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D004492:Edetic Acid; D005947:Glucose; D002118:Calcium