Radioligand binding of antagonists of platelet‐activating factor to intact human platelets
Open Access
- 15 February 1988
- journal article
- Published by Wiley in FEBS Letters
- Vol. 228 (2) , 285-289
- https://doi.org/10.1016/0014-5793(88)80017-6
Abstract
Two new antagonists of platelet‐activating factor (PAF), the pyrrolothiazole derivative 52770 RP and the triazolodiazepine WEB 2086, have been studied as radioligands in intact human platelets. [3H]52770 RP and [3H]WEB 2086 bound specifically to high‐affinity sites with dissociation constants (K d) of 14.8 and 6.1 nM, respectively. The maximal number of sites for [3H]52770 RP binding was approx. 15‐fold higher than for [3H]PAF and [3H]WEB 2086. In addition, C16‐PAF, lyso‐PAF, WEB 2086 and 52770 RP had K i values which were nearly identical for both [3H]PAF and [3H]WEB 2086, whereas only 52770 RP competed for [3H]52770 RP‐binding sites. These results demonstrate that in human platelets the sites of [3H]WEB 2086 binding are identical to [3H]PAF‐binding sites, whereas those of [3H]52770 RP are not. [3H]WEB 2086 appears, therefore, to be a suitable antagonist radioligand for labelling PAF receptors.Keywords
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