| Necessity of ascorbic acid in the radioligand binding assay for [3H]5-hydroxytryptamine. | |
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MedLine Citation:
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PMID: 3774116 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Evidence is presented to suggest that ascorbic acid is required in the radioligand binding assay for [3H]5-hydroxytryptamine ([3H]5-HT, [3H]serotonin). In the absence of ascorbic acid, oxidation of [3H]5-HT occurred if the radioligand solution was left on ice for 1 or 3 hr. The oxidative products were detectable by thin-layer chromatography. They increased the binding significantly, although there was only slight oxidation (less than 1%) of the [3H]5-HT. When ascorbic acid was not used in the radioligand binding assay for [3H]5-HT, even though [3H]5-HT was prepared immediately before incubating with the membranes from the cortex of the rat, the binding also increased. The increased binding of [3H]5-HT had a low affinity (Kd = 14 nM) and high B max (1180 fmol/mg protein), compared to that in the presence of ascorbic acid (Kd = 5 nM; B max = 210 fmol/mg protein). However, the increased binding was not receptor-related because the additional radioactivity was not displaceable by excess of unlabelled 5-HT (10 microM) or d-LSD (d-lysergic acid iethylamide) and anomalous "specific binding" occurred in boiled membranes from cortex, in which the binding sites for 5-HT were destroyed. These results suggest that oxidation of [3H]5-HT may occur during the incubation with membranes and that ascorbic acid is therefore required as an antioxidant. |
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Authors:
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J W Andresen; J C Shih |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Neuropharmacology Volume: 25 ISSN: 0028-3908 ISO Abbreviation: Neuropharmacology Publication Date: 1986 Aug |
Date Detail:
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Created Date: 1986-11-24 Completed Date: 1986-11-24 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0236217 Medline TA: Neuropharmacology Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 869-75 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Ascorbic Acid / pharmacology* Cerebral Cortex / analysis*, metabolism Male Oxidation-Reduction Radioligand Assay Rats Rats, Inbred Strains Receptors, Serotonin / analysis*, metabolism Serotonin / metabolism* |
| Grant Support | |
ID/Acronym/Agency:
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MH37020/MH/NIMH NIH HHS; MH39085/MH/NIMH NIH HHS; S07 RR05792/RR/NCRR NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Receptors, Serotonin; 50-67-9/Serotonin; 50-81-7/Ascorbic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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