Human platelet [125I]R-DOI binding sites. Characterization by in vitro autoradiography |
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Authors: | A Himeno J M Saavedra |
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Affiliation: | Section on Pharmacology, National Institute of Mental Health, Bethesda, MD 20892. |
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Abstract: | We quantified binding sites for 2,5-dimethoxy-4-iodo-phenylisopropylamine (DOI), a 5-HT2 agonist and hallucinogen, in human platelets. We incubated sections from human platelet pellets with [125I]R-DOI with or without 1 mumol/L ketanserin, followed by autoradiography and computerized microdensitometry. We corrected the values of binding density by the protein content of each section with a densitometric protein assay. The present method revealed a single class of high affinity binding sites for [125I]R-DOI, with a Kd of 6.4 +/- 0.7 nmol/L and a Bmax of 100 +/- 10 fmol/mg protein. Kd and Bmax for [125I]R-DOI determined by the classical membrane binding assay, were 2.7 +/- 0.4 nmol/L and 100 +/- 10 fmol/mg protein, respectively. The present method is precise, very sensitive, and allows the characterization of [125I]R-DOI binding in sections obtained from as little as 3 ml of blood. Standardization is possible after correction by the protein content of each individual section. |
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