Abstract
[3H]-BAY U 3405 was used to characterize the pH-dependency of the binding of various ligands to the TXA2/PGH2-receptor of human platelet membranes. Maximum binding of [3H]-BAY U 3405 is achieved at pH 5.8. In inhibition studies the ligands Daltroban, CTA2, and U 46619 also show a higher affinity at pH 5.8 compared to pH 7.4. In contrast, the ligands I-PTA-OH and GR 32191 have a higher affinity at pH 7.4. No difference is seen with SQ 29548. The ligands I-PTA-OH, GR 32191, and SQ 29548 have a second protonable group in common, which is thought to be the reason for the different pH-dependent binding.
MeSH terms
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15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
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Blood Platelets / metabolism*
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Carbazoles / pharmacology
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Cell Membrane / metabolism
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Humans
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Hydrogen-Ion Concentration
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In Vitro Techniques
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Kinetics
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Ligands
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Phenylacetates / pharmacology
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Platelet Aggregation Inhibitors / pharmacology
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Prostaglandin Endoperoxides, Synthetic / metabolism*
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Prostaglandin Endoperoxides, Synthetic / pharmacology
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Prostaglandin H2
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Prostaglandins H / metabolism*
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Receptors, Prostaglandin / metabolism*
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Receptors, Thromboxane
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Sulfonamides / pharmacology
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Thromboxane A2 / metabolism*
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Thromboxanes / antagonists & inhibitors
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Vasoconstrictor Agents / pharmacology
Substances
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Carbazoles
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Ligands
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Phenylacetates
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Platelet Aggregation Inhibitors
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Prostaglandin Endoperoxides, Synthetic
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Prostaglandins H
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Receptors, Prostaglandin
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Receptors, Thromboxane
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Sulfonamides
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Thromboxanes
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Vasoconstrictor Agents
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Prostaglandin H2
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Thromboxane A2
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15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
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ramatroban
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daltroban