Plasma ectonucleotidases prevent desensitization of purinergic receptors in stored platelets: importance for platelet activity during thrombus formation.
Transfusion
; 46(6): 1018-28, 2006 Jun.
Article
em En
| MEDLINE
| ID: mdl-16734820
ABSTRACT
BACKGROUND:
Platelets (PLTs) contain purinergic receptors for ATP (P2X1) and ADP (P2Y1 and P2Y12) that rapidly desensitize upon stimulation with these nucleotides. In vivo, this is antagonized by ectonucleotidases on the surface of endothelial cells and white blood cells (WBCs). The receptor desensitization of ATP- and ADP-induced responses of PLTs stored in plasma without WBCs was investigated. STUDY DESIGN ANDMETHODS:
ATP- and ADP-induced PLT shape change (shear-induced) aggregation and Ca2+ signaling were measured in the presence or absence of plasma. Degradation of nucleotides in plasma was quantified by high-performance liquid chromatography.RESULTS:
Washed PLTs became refractory for ATP and ADP in shape change, aggregation, and Ca2+ responses during a 90-minute incubation at 37 degrees C. The PLT responses mediated by P2X1, P2Y1, and P2Y12 receptors gradually reduced or disappeared. When plasma was present, however, the PLTs persistently showed high responses to ATP and ADP. Heat treatment of plasma abolished this effect. Also under conditions of flow and high shear, PLTs in plasma kept high P2X1 activity, mediating aggregate formation. In isolated plasma, not containing WBCs, nucleotides were degraded in the order of ADP/UDP>ATP/UTP. Degradation of ATP was partly inhibited by blocking the ecto-NTPDase CD39, whereas degradation of both ATP and ADP was inhibited by blocking ectopyrophosphatase/phosphodiesterase activity. Part of the nucleotide-degrading activities appeared to be membrane-bound.CONCLUSION:
Ectonucleotidases in plasma preserve the functionality of P2X1 and P2Y receptors. Upon PLT storage, these plasma activities are essential to ensure adequate (shear-dependent) formation of aggregates and thrombi.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pirofosfatases
/
Trombose
/
Plaquetas
/
Preservação de Sangue
/
Receptores Purinérgicos
Limite:
Humans
Idioma:
En
Revista:
Transfusion
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Holanda