多种信号途径介导花生四烯酸与5-羟色胺在促人类血小板凝集中的协同作用

AIM: To examine the signalling mechanisms involved in the synergistic interaction of 5-hydroxytryptamine (5-HT) and arachidonic acid (AA) in human platelet aggregation. METHODS: Blood was obtained from healthy human subjects, mixed with 3.8 % sodium citrate (9:1), and centrifuged to prepare platelet rich plasma (PRP). Aggregation was monitored using a Dual-channel Lumi-aggregometer. The agonist-induced influx of Ca^2 was measured using Fura-2 AM. TXA2 formation was studied using radiochemical method. RESULTS: Subthreshold concentration of 5-HT (2μmol/L) potentiated the effect of low dose of AA (0.2 mmol/L) in human platelets. This synergistic effect was blocked by 5-HT2 receptor antagonist (methysergide IC50=5.2 nmol/L; cyproheptadine IC50=0.6 nmol/L), and thromboxane A2 receptor antagonist (SQ 29 548; IC5o=30 nmol/L), showing that the effect is receptor-mediated.To examine the down-stream signalling pathways, we found that such an interaction was inhibited by calcium channel blockers (diltiazem; IC50=3 μmol/L and verapamil; IC50=5 μmol/L), phospholipase C (PLC) inhibitor (U73122;IC50=4 μmol/L), cyclooxygenase inhibitor, (indomethacin; IC50=0.2 μmol/L) and mitogen-activated protein (MAP) kinase inhibitor (PD98059; IC5o=3 ktmol/L). The effect was also inhibited by a specific tyrosine light chain kinase(TLCK) inhibitor, herbimycin A with IC50 value of 5 μmol/L. Pretreatment of platelet with 5-HT and AA induced rise in intracellular calcium and this effect was blocked by verapamil. CONCLUSION: The synergism between 5-HT and AA in platelet aggregation involves activation of PLC/Ca^2 , COX, and MAP kinase pathways.

Synergism interaction between arachidonic acid by 5-hydroxytryptamine in human platelet aggregation is mediated through multiple signalling pathways

AIM: To examine the signalling mechanisms involved in the synergistic interaction of 5-hydroxytryptamine (5-HT) and arachidonic acid (AA) in human platelet aggregation. METHODS: Blood was obtained from healthy human subjects, mixed with 3.8 % sodium citrate (9:1), and centrifuged to prepare platelet rich plasma (PRP). Aggregation was monitored using a Dual-channel Lumi-aggregometer. The agonist-induced influx of Ca2+ was measured using Fura-2 AM. TXA2 formation was studied using radiochemical method. RESULTS: Subthreshold concentration of 5-HT (2 micromol/L) potentiated the effect of low dose of AA (0.2 mmol/L) in human platelets. This synergistic effect was blocked by 5-HT2 receptor antagonist (methysergide IC(50)=5.2 nmol/L; cyproheptadine IC(50)=0.6 nmol/L), and thromboxane A2 receptor antagonist (SQ 29 548; IC(50)=30 nmol/L), showing that the effect is receptor-mediated. To examine the down-stream signalling pathways, we found that such an interaction was inhibited by calcium channel blockers (diltiazem; IC(50)=3 micromol/L and verapamil; IC(50)=5 micromol/L), phospholipase C (PLC) inhibitor (U73122; IC50=4 micromol/L), cyclooxygenase inhibitor, (indomethacin; IC(50)=0.2 micromol/L) and mitogen-activated protein (MAP) kinase inhibitor (PD98059; IC(50)=3 micromol/L). The effect was also inhibited by a specific tyrosine light chain kinase (TLCK) inhibitor, herbimycin A with IC(50) value of 5 micromol/L. Pretreatment of platelet with 5-HT and AA induced rise in intracellular calcium and this effect was blocked by verapamil. CONCLUSION: The synergism between 5-HT and AA in platelet aggregation involves activation of PLC/Ca2+, COX, and MAP kinase pathways.