Research Article| Volume 85, ISSUE 3, P207-215, February 01, 1997



      Picotamide is a dual TxA2 receptor antagonist/Tx A2 synthetase inhibitor. As the picotamide effect is maximum only after 5–10 min of incubation, aim of the present work was to study whether the effect of picotamide could be observed even after wash out of the drug from the external buffer. Platelet aggregation, serotonin release and changes in intracellular calcium were analyzed in platelets treated with picotamide and then gel-filtered, in comparison with gel-filtered platelets treated with picotamide. To exclude the possibility that the inhibitory effect of picotamide is due to its intracytosolic storage, serotonin release in digitonin-permeabilized platelets was measured. Platelet aggregation and serotonin release in response either to U46619, a synthetic agonist of the thromboxane A2 receptor, or arachidonic acid or collagen, as well as the changes in intracellular calcium concentration after U46619 or arachidonic acid stimulation, were inhibited by picotamide even when it had been washed out by gel-filtration. Both inhibitions were very similar to that observed in experiments in which picotamide was present in the medium. As the serotonin release in digitonin permeabilized platelets presented the same inhibition it may be excluded that picotamide effect is consequent upon the cytosolic storage of the drug. Since our results clearly indicate that the action of picotamide persists even after washing out of the drug from the medium, the idea that this antagonistic effect may be dependent on its binding to platelet plasma membrane rather than on its cytosolic concentration, is strongly substantiated. Copyright © 1997 Elsevier Science Ltd


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Thrombosis Research
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • GRESELE P
        • DECKMYN H
        • ARNOUT J
        • NENCI G.G
        • VERMYLEN J
        Characterization of N,N′-bis(3-Picolyl)-4-Methoxy-Isophthalamide (Picotamide) as a dual Thromboxane Synthase Inhibitor/Thromboxane A2 Receptor Antagonist in Human Platelets.
        Thromb Haemostas. 1989; 61: 479-484
        • CATTANEO M
        • TENCONI P.M
        • LECCHI A
        • MANNUCCI P.M
        In Vitro Effects of Picotamide on Human Platelet Aggregation, the Release Reaction and Thromboxane B2 Production.
        Thromb Res. 1991; 62: 717-724
        • VIOLI F
        • GHISELLI A
        • IULIANO L
        • PRATICO′ D
        • ALESSANDRI C
        • BALSANO F
        Inhibition by Picotamide of Thromboxane Production In Vitro and Ex Vivo.
        Eur J Clin Pharmacol. 1988; 33: 599-602
        • MODESTI P.A
        • CECIONI I
        • COLELLA A
        • COSTOLI A
        • PANICCIA R
        • NERI SERNERI G.G
        Binding kinetics and antiplatelet activities of picotamide, a thromboxane A2 receptor antagonist.
        Br J Pharmacol. 1994; 112: 81-86
        • MODESTI P.A
        • COLELLA A
        • ABBATE R
        • GENSINI G.F
        • NERI SERNERI G.G
        Competitive Inhibition by Picotamide of Platelet Thromboxane A2 Receptor Binding.
        Eur J Pharmacol. 1989; 169: 85-93
        • MODESTI P.A
        • COLELLA A
        • CECIONI I
        • GENSINI G.F
        • ABBATE R
        • NERI SERNERI G.G
        Acute Reduction of TxA2 platelet binding sites after in vivo administration of a TxA2 receptor inhibitor.
        Br J Clin Pharmacol. 1991; 31: 439-443
        • PULCINELLI F.M
        • PIGNATELLI P
        • RIONDINO S
        • PARISI S
        • GAZZANIGA P.P
        Effect of picotamide on the calcium mobilization and phospholipase C activation in human platelets.
        Thromb Res. 1994; 74: 453-461
        • ASTER R.H
        • JANDEL J.H
        Platelet Sequestration in Man.
        J Clin Invest. 1964; 43: 834-855
        • BORN G.V.R
        The aggregation of blood platelets by adenosine diphosphate and its reversal.
        Nature. 1962; 194: 405-407
        • COSTA J.J
        • MURPHY D.L
        Platelet 5-HT uptake and release stopped rapidly by formaldehyde.
        Nature. 1975; 255: 405-407
        • POENIE M
        • TSIEN R.Y
        A New Generation of Ca2+ Indicators with Greatly Improved Fluorescence Properties.
        J Biol Chem. 1985; 260: 3440-3445
      1. DANIEL, J.L., SELAK, M.A., PURDON, A.D. and SALGANICOFF, L. Methods for the study of the role of calcium in platelet function. In: Methods for studying platelets and megakaryocytes. Colman, R.W. and Smith, J.B (eds.), pp. 185–215, Alan R. Liss Inc., New York (1987).

        • PERRIN D.D
        • SAYCE I.G
        Computer calculation of equilibrium concentrations in mixtures of metal ions and complexing species.
        Talanta. 1967; 14: 833-842
        • HASLAM R.J
        • DAVIDSON M.M.L
        Guanine nucleotides decrease the free [Ca2+] required for secretion of serotonin from permeabilized blood platelets. Evidence of a role for a GTP-binding protein in platelet activation.
        FEBS lett. 1984; 174: 90-95
        • DORN G.W
        Mechanism for homologous downregulation of thromboxane A2 receptors in cultured human chronic myelogenous leukemia (K562) cells.
        J Pharmacol Exp Ther. 1991; 259: 228-234
        • ISHIGURO S
        • ARII S
        • MONDEN K
        • FUJITA S
        • NAKAMURA T
        • NIWANO M
        • HARADA T
        • USHIKUBI F
        • NARUMIYA S
        • IMAMURA M
        Involvement of thromboxane A2-thromboxane A2 receptor system of the hepatic sinusoid in pathogenesis of cold preservation/reperfusion injury in the rat liver graft.
        Transplantation. 1995; 59: 957-961
        • ARMSTRONG R.A
        • HUMPHREY P.P.A
        • LUMLEY P
        Reduction in the number of thromboxane receptors on human platelets after exposure to GR32191.
        Br J Pharmacol. 1993; 110: 548-552