A1 Refereed original research article in a scientific journal
AGING EFFECT ON NEUTRAL AMINO-ACID-TRANSPORT AT THE BLOOD-BRAIN-BARRIER MEASURED WITH L-[2-F-18]-FLUOROPHENYLALANINE AND PET
Authors: ITO H, HATAZAWA J, MURAKAMI M, MIURA S, IIDA H, BLOOMFIELD PM, KANNO I, FUKUDA H, UEMURA K
Publisher: SOC NUCLEAR MEDICINE INC
Publication year: 1995
Journal: Journal of Nuclear Medicine
Journal name in source: JOURNAL OF NUCLEAR MEDICINE
Journal acronym: J NUCL MED
Volume: 36
Issue: 7
First page : 1232
Last page: 1237
Number of pages: 6
ISSN: 0161-5505
Abstract
Neutral amino acids (NAAs) are transported from the blood to the brain using the same carrier system in a competitive fashion. The purpose of this study is to establish a method for evaluating neutral amino acid transport at the blood-brain barrier (BBB) in humans and to examine the aging effect of amino add transport. Methods: A dynamic PET study with L-(2-F-18)-fluorophenylalanine (F-18-Phe) was performed in 14 normal volunteers (age 21-71 yr; mean +/- s.d., age range 48.0 +/- 17.1 yr). By using a two-compartment model analysis and a weighted integration technique, the influx rate constant K-1, the efflux rate constant k(2) and distribution volume V-d of F-18-Phe were estimated in various brain structures. Results: The value of K, was inversely correlated with plasma NAA concentration (r = -0.69, p < 0.01). The cerebellum showed the highest value of K-1, while the white matter showed the lowest. There was no significant change in K-1 during aging. The value of k(2) was significantly increased with age. Conclusion: No decline of K-1 during aging indicated that NAA transport from the blood to the brain is a limiting process of age in amino acid incorporation. Fluorine-18-Phe PET imaging is a feasible method to study NAA transport at the BBB in vivo in humans and can be applied to pathological conditions of the brain.
Neutral amino acids (NAAs) are transported from the blood to the brain using the same carrier system in a competitive fashion. The purpose of this study is to establish a method for evaluating neutral amino acid transport at the blood-brain barrier (BBB) in humans and to examine the aging effect of amino add transport. Methods: A dynamic PET study with L-(2-F-18)-fluorophenylalanine (F-18-Phe) was performed in 14 normal volunteers (age 21-71 yr; mean +/- s.d., age range 48.0 +/- 17.1 yr). By using a two-compartment model analysis and a weighted integration technique, the influx rate constant K-1, the efflux rate constant k(2) and distribution volume V-d of F-18-Phe were estimated in various brain structures. Results: The value of K, was inversely correlated with plasma NAA concentration (r = -0.69, p < 0.01). The cerebellum showed the highest value of K-1, while the white matter showed the lowest. There was no significant change in K-1 during aging. The value of k(2) was significantly increased with age. Conclusion: No decline of K-1 during aging indicated that NAA transport from the blood to the brain is a limiting process of age in amino acid incorporation. Fluorine-18-Phe PET imaging is a feasible method to study NAA transport at the BBB in vivo in humans and can be applied to pathological conditions of the brain.
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