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Evaluation of 13N-amines as tracers.
T Tominaga1, O Inoue, K Suzuki
1Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
International Journal of Radiation Applications and Instrumentation. Part B, Nuclear Medicine and Biology
|January 1, 1987
Summary
13N-labeled amines are rapidly distributed in tissues and metabolized by monoamine oxidase (MAO). The resulting 13N-ammonia is converted to amino acids, making these amines potential metabolic trapping tracers for amine studies.
Area of Science:
- Biochemistry
- Pharmacology
- Radiochemistry
Background:
- Understanding the metabolic fate and organ distribution of amine compounds is crucial in pharmacology.
- Nitrogen-13 (13N) labeled compounds offer unique insights into metabolic pathways due to their short half-life and positron emission.
Purpose of the Study:
- To investigate the organ distribution and metabolic fate of three specific 13N-labeled amines: 13N-beta-phenethylamine, 13N-n-octylamine, and 13N-3,4-dimethoxyphenethylamine.
- To evaluate the potential of these 13N-amines as metabolic trapping tracers.
Main Methods:
- Administration of 13N-labeled amines to biological systems.
- Analysis of tissue distribution and metabolic products.
- Enzymatic assays to identify metabolic pathways, including monoamine oxidase (MAO) activity and glutamine synthetase conversion.
Main Results:
- 13N-amines exhibited rapid transfer to various tissues post-administration.
- Significant oxidation of 13N-amines by MAO was observed.
- The generated 13N-ammonia was efficiently converted into amino acids, primarily glutamine, via glutamine synthetase and subsequently trapped in tissues.
Conclusions:
- 13N-labeled amines are rapidly distributed and metabolized in tissues.
- The metabolic trapping of 13N-ammonia into amino acids suggests a viable mechanism for studying amine disposition and metabolism.
- These findings support the potential utility of 13N-amines as metabolic trapping tracers in biochemical and pharmacological research.