Document Detail

Aging effect on neutral amino acid transport at the blood-brain barrier measured with L-[2-18F]-fluorophenylalanine and PET.
MedLine Citation:
PMID:  7790949     Owner:  NLM     Status:  MEDLINE    
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 acid transport. METHODS: A dynamic PET study with L-(2-18F)-fluorophenylalanine (18F-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 K1, the efflux rate constant k2 and distribution volume Vd of 18F-Phe were estimated in various brain structures. RESULTS: The value of K1 was inversely correlated with plasma NAA concentration (r = -0.69, p < 0.01). The cerebellum showed the highest value of K1, while the white matter showed the lowest. There was no significant change in K1 during aging. The value of k2 was significantly increased with age. CONCLUSION: No decline of K1 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.
H Ito; J Hatazawa; M Murakami; S Miura; H Iida; P M Bloomfield; I Kanno; H Fukuda; K Uemura
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of nuclear medicine : official publication, Society of Nuclear Medicine     Volume:  36     ISSN:  0161-5505     ISO Abbreviation:  J. Nucl. Med.     Publication Date:  1995 Jul 
Date Detail:
Created Date:  1995-07-27     Completed Date:  1995-07-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0217410     Medline TA:  J Nucl Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1232-7     Citation Subset:  IM    
Department of Radiology and Nuclear Medicine, Research Institute for Brain and Blood Vessels, Akita, Japan.
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MeSH Terms
Aging / metabolism*
Amino Acids / metabolism*
Biological Transport
Blood-Brain Barrier*
Brain / metabolism,  radionuclide imaging
Carbon Radioisotopes / diagnostic use
Middle Aged
Phenylalanine / analogs & derivatives*,  diagnostic use
Tomography, Emission-Computed*
Reg. No./Substance:
0/Amino Acids; 0/Carbon Radioisotopes; 325-69-9/2-fluorophenylalanine; 63-91-2/Phenylalanine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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