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Diadenosine polyphosphates induce intracellular Ca 2+ mobilization in human neutrophils via a pertussis toxin sensitive G‐protein‘pa
Author(s) -
GASMI L.,
MCLENNAN A. G.,
EDWARDS S. W.
Publication year - 1997
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1997.00123.x
Subject(s) - pertussis toxin , intracellular , toxin , mobilization , g protein , chemistry , microbiology and biotechnology , biology , biochemistry , receptor , archaeology , history
The diadenosine polyphosphates diadenosine 5′,5′′′‐ P 1 , P 3 ‐triphosphate(Ap 3 A), diadenosine 5′,5′′′‐ P 1 , P 4 ‐tetraphosphate (Ap 4 A), diadenosine 5′,5′′′‐ P 1 , P 5 ‐pentaphosphate (Ap 5 A) and diadenosine 5′,5′′′‐ P 1 , P 6 ‐hexaphosphate (Ap 6 A) all stimulated increases in intracellular Ca 2+ in human neutrophils. Maximal increases in intracellular Ca 2+ of 650 nm were obtained at dinucleotide concentrations of 500–700 μ m. These increases in intracellular Ca 2+ were completely abolished by pre‐treatment of the neutrophils with pertussis toxin and were hardly affected when the extracellular buffer was devoid of Ca. 2+ On the other hand, adenosine triphosphate (ATP) could stimuate much greater increases in intracellular Ca 2+ (up to 1·1 μ m) at much lower concentrations (half maximal responses obtained at around 5 μ m ATP). Receptor de‐sensitization experiments indicate that human neutrophils may possess two types of P2‐purinoceptors. The first of these may bind ATP (but not the dinucleotides) with high affinity whilst the second may bind the dinucleotides with lower affinity and also bind ATP.