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Radioisotopic studies of the binding, exchange, and distribution of 5‐hydroxytryptamine synthesized from its radioactivity precursor
Author(s) -
Gershon M. D.,
Ross L. L.
Publication year - 1966
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1966.sp008046
Subject(s) - compartmentalization (fire protection) , chemistry , metabolism , metabolite , radiochemistry , biochemistry , labelling , tissue distribution , specific activity , enzyme , biology , physiology
1. The synthesis, distribution, storage, and subsequent metabolism of 5‐hydroxytryptamine (5‐HT) produced in mice from the administration of its radioactive precursor, 5‐hydroxytryptophan, has been investigated to form the basis for a similar study to be conducted by radioautography. 2. Intravenous injection of the radioactive material was found to be essential for significant uptake of radioactivity by tissue. The duration of the period during which radioactive material was available for uptake by the tissue was 2 hr. 3. The relative distribution of radioactivity in individual organs was studied and the radioactive compounds present in each were identified and quantitatively assayed. No unrelated routes of metabolism of the labelled material were found and radioautographic results may be interpreted in terms of the metabolic picture which emerged. 4. Radioactive 5‐HT was bound in tissues in preference to both its precursor, and metabolite, 5‐hydroxytryptamine‐O‐glucuronide, and the radioactive 5‐HT produced in vivo after the injection of labelled 5‐hydroxytryptophan probably entered and labelled the endogenous 5‐HT pool. 5. Fixatives prepared with buffer solutions made hypertonic by the addition of sucrose could rapidly and effectively halt the movement of radioactive 5‐HT out of tissues and prevent its subsequent extraction during histological processing. 6. It is concluded that localization of sites concerned with 5‐HT metabolism by means of radioautography is feasible and the 5‐HT so localized will probably reflect the physiological compartmentalization of the amine.