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Pharmacology, Toxicology and Environmental Health

Aga Khan University

Series

5-hydroxytryptamine

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Full-Text Articles in Physiology

Co-Activation Of Gi And Gq Proteins Exerts Synergistic Effect On Human Platelet Aggregation Through Activation Of Phospholipase C And Ca2+ Signalling Pathways, B H. Shah, A Siddiqui, K A. Qureshi, M Khan, S Rafi, V A. Ujan, M Y. Yakoob, Y Yaqub, H Rasheed, S A. Saeed Mar 1999

Co-Activation Of Gi And Gq Proteins Exerts Synergistic Effect On Human Platelet Aggregation Through Activation Of Phospholipase C And Ca2+ Signalling Pathways, B H. Shah, A Siddiqui, K A. Qureshi, M Khan, S Rafi, V A. Ujan, M Y. Yakoob, Y Yaqub, H Rasheed, S A. Saeed

Department of Biological & Biomedical Sciences

Our previous studies have shown that subthreshold concentrations of two platelet agonists exert synergistic effects on platelet aggregation. Here we studied the mechanism of synergistic interaction of 5-hydroxytryptamine (5-HT) and epinephrine mediated platelet aggregation. We show that 5-HT had no or little effect on aggregation but it did potentiate the aggregation response of epinephrine. The synergistic interaction of 5-HT (1-5 microM) and epinephrine (0.5-2 microM) was inhibited by alpha2-adrenoceptor blocker (yohimbine; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 mM, respectively), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 …