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α‐granule secretion from α‐toxin permeabilized, MgATP‐exposed platelets is induced independently by H + and Ca 2+
Author(s) -
Flaumenhaft Robert,
Furie Bruce,
Furie Barbara C.
Publication year - 1999
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199904)179:1<1::aid-jcp1>3.0.co;2-e
Subject(s) - granule (geology) , secretion , dense granule , platelet , gtp' , microbiology and biotechnology , biology , chemistry , biochemistry , biophysics , platelet activation , enzyme , immunology , paleontology
In order to better understand granule release from platelets, we developed an α‐toxin permeabilized platelet model to study α‐granule secretion. Secretion of α‐granules was analyzed by flow cytometry using P‐selectin as a marker for α‐granule release. P‐selectin surface expression occurred when platelets were permeabilized in the presence of Ca 2+ . Responsiveness to Ca 2+ was lost 30 min after permeabilization but could be reconstituted with MgATP. α‐toxin–permeabilized, MgATP‐exposed platelets also degranulated within a pH range of 5.4–5.9 without exposure to and independent of Ca 2+ . ATP, GTP, CTP, UTP, and ITP supported Ca 2+ ‐induced α‐granule secretion, while H + ‐induced α‐granule secretion occurred only with ATP and GTP. Both Ca 2+ ‐ and H + ‐induced α‐granule secretion required ATP hydrolysis. Kinase inhibitors blocked both Ca 2+ ‐ and H + ‐induced secretion. These data suggest that α‐granule secretion in this permeabilized platelet system shares many characteristics with granule secretion studied in other permeabilized cell models. Furthermore, these results show that H + can trigger α‐granule release independent of Ca 2+ . J. Cell. Physiol. 179:1–10, 1999. © 1999 Wiley‐Liss, Inc.