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

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(英文)

作　　者：Sheikh Arshad SAEED Huma RASHEED Anwar-ul-Hassan GILANI 

机构地区：[1]Department of Biological and Biomedical Sciences The Aga Khan University PO Box 3500 Stadium Road Karachi 748700 Pakistan,Department of Biological and Biomedical Sciences The Aga Khan University PO Box 3500 Stadium Road Karachi 748700 Pakistan,Department of Biological and Biomedical Sciences The Aga Khan University PO Box 3500 Stadium Road Karachi 748700 Pakistan

出　　处：《Acta Pharmacologica Sinica》2003年第10期958-964,1060,共8页中国药理学报（英文版）

基　　金：Project supported by the research funds from the Aga Khan University, Karachi.

摘　　要：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. TXA_2 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-HT_2 receptor antagonist (methysergide IC_(50)=5.2 nmol/L; cyproheptadine IC_(50)=0.6 nmol/L), and thromboxane A_2 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 μmol/L and verapamil; IC_(50)=5 μmol/L), phospholipase C (PLC) inhibitor (U73122; IC_(50)=4 μmol/L), cyclooxygenase inhibitor, (indomethacin; IC_(50)=0.2 μmol/L) and mitogen-activated protein (MAP) kinase inhibitor (PD98059; IC_(50)=3 μmol/L). The effect was also inhibited by a specific tyrosine light chain kinase (TLCK) inhibitor, herbimycin A with IC_(50) 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.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.

关 键 词：SEROTONIN arachidonic acids platelet aggregation cyclooxygenase inhibitors METHYSERGIDE CYPROHEPTADINE thromboxane A_2 phospholipase C CALCIUM drug synergism 

分 类 号：R33[医药卫生—人体生理学]