RESUMO
S-Nitroso-cysteine (SNC), a putative endothelium-derived relaxing factor, potently inhibited collagen- and arachidonic acid-induced platelet aggregation (IC50=100 nM) and thromboxane A2 (TxA2) synthesis of human blood platelets. ODQ, a selective inhibitor of the soluble guanylyl cyclase, inhibited SNC-induced formation of cGMP but did not reverse inhibition by SNC of collagen- and arachidonic acid-induced platelet aggregation. Combination of ODQ with SQ-29548, a specific platelet TxA2 receptor antagonist, did not modify the antiaggregatory action of SNC. Our study shows that SNC inhibits platelet aggregation by cGMP-independent mechanisms that may involve inhibition of TxA2 synthesis in human platelets.
Assuntos
Plaquetas/metabolismo , GMP Cíclico/metabolismo , Cisteína/análogos & derivados , Compostos Nitrosos/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Agregação Plaquetária/efeitos dos fármacos , S-Nitrosotióis , Tromboxano A2/biossíntese , Ácido Araquidônico/farmacologia , Aspirina/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes , Colágeno/farmacologia , Cisteína/metabolismo , Cisteína/farmacologia , Ácidos Graxos Insaturados , Glutationa/análogos & derivados , Glutationa/metabolismo , Guanilato Ciclase/antagonistas & inibidores , Humanos , Hidrazinas/farmacologia , Concentração Inibidora 50 , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Nitroprussiato/farmacologia , Compostos Nitrosos/metabolismo , Oxidiazóis/farmacologia , Inibidores da Agregação Plaquetária/metabolismo , Quinoxalinas/farmacologia , S-NitrosoglutationaRESUMO
A fully validated gas chromatographic-tandem mass spectrometric (GC-MS-MS) method is described for the accurate determination of acetylsalicylic acid (ASA) in human plasma after a single low-dose oral administration of aspirin or guaimesal, an ASA releasing prodrug. ASA and the newly prepared O-[2H3]-acetylsalicylic acid (d3-ASA) used as internal standard were determined in 100-microl aliquots of plasma by extractive pentafluorobenzyl (PFB) esterification using PFB bromide and tetrabutylammoniumhydrogen sulphate as the esterifying and ion-pairing agent, respectively, and by GC-MS-MS analysis in the negative-ion chemical ionization mode. The overall relative standard deviations were below 8% for ASA levels in the range 0-1 microg/ml plasma. Mean accuracy was 3.8% for ASA levels within the range 0-100 ng/ml. The limit of quantitation of the method was determined as 200 pg/ml ASA at an accuracy of 5.5% and a precision of 15.2%. The limit of detection was determined as 546 amol of ASA at a signal-to-noise ratio of 10:1.
