Human platelet [125I]R-DOI binding sites. Characterization by in vitro autoradiography.
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.
Himeno
A
A
Section on Pharmacology, National Institute of Mental Health, Bethesda, MD 20892.
Saavedra
J M
JM
D000328:Adult; D000662:Amphetamines / Q000097:blood*; D001345:Autoradiography / Q000379:methods; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007650:Ketanserin / Q000097:blood / Q000494:pharmacology; D007700:Kinetics; D008238:Lysergic Acid Diethylamide / Q000097:blood; D008297:Male; D011985:Receptors, Serotonin / Q000378:metabolism*; D013237:Stereoisomerism
D000662:Amphetamines; D007457:Iodine Radioisotopes; D011985:Receptors, Serotonin; D008238:Lysergic Acid Diethylamide; D007650:Ketanserin; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine