α-granule secretion from α-toxin permeabilized, MgATP-exposed platelets is induced independently by H+ and Ca2+
✍ Scribed by Robert Flaumenhaft; Bruce Furie; Barbara C. Furie
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 199 KB
- Volume
- 179
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
In order to better understand granule release from platelets, we developed an ␣-toxin permeabilized platelet model to study ␣-granule secretion. Secretion of ␣-granules was analyzed by flow cytometry using P-selectin as a marker for ␣-granule release. P-selectin surface expression occurred when platelets were permeabilized in the presence of Ca 2ϩ . Responsiveness to Ca 2ϩ was lost 30 min after permeabilization but could be reconstituted with MgATP. ␣-toxin-permeabilized, MgATP-exposed platelets also degranulated within a pH range of 5.4 -5.9 without exposure to and independent of Ca 2ϩ . ATP, GTP, CTP, UTP, and ITP supported Ca 2ϩ -induced ␣-granule secretion, while H ϩ -induced ␣-granule secretion occurred only with ATP and GTP. Both Ca 2ϩ -and H ϩ -induced ␣-granule secretion required ATP hydrolysis. Kinase inhibitors blocked both Ca 2ϩ -and H ϩ -induced secretion. These data suggest that ␣-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 ϩ can trigger ␣-granule release independent of Ca 2ϩ .