title: A new radiopharmaceutical for the cerebral dopaminergic presynaptic function: 6-radioiodinated L-meta-tyrosine.
abstract: Geometric isomers of radioiodinated L-meta-tyrosine, 6-[I-125]iodo-and 4-[1-125]iodo-L-meta-tyrosine (6-I-L-mTyr, 4-I-L-mTyr) were separated by high-performance liquid chromatography . Both 6-I- and 4-I-L-mTyr had high energy-dependent brain accumulation. 6-I- and 4-I-L-mTyr were also metabolically stable and were rapidly excreted through the urine. 6-I-L-mTyr had a predilection for the cerebral aromatic L-amino acid decarboxylase (DOPA decarboxylase), the final enzyme of dopamine biosynthesis. 6-Radioiodinated L-mTyr is a new radiopharmaceutical that can be both useful in assessing cerebral amino acid transport mechanism and quantifying metabolically active DOPA decarboxylase.
authors.affiliation: Department of Radiology, Miyazaki Medical College, Miyazaki-gun, Japan.
authors.forename: L G
authors.initials: LG
authors.lastname: Flores
authors.forename: K
authors.initials: K
authors.lastname: Kawai
authors.forename: M
authors.initials: M
authors.lastname: Nakagawa
authors.forename: N
authors.initials: N
authors.lastname: Shikano
authors.forename: S
authors.initials: S
authors.lastname: Jinnouchi
authors.forename: S
authors.initials: S
authors.lastname: Tamura
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.forename: A
authors.initials: A
authors.lastname: Kubodera
mesh_terms: D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006834:Hydrazines / Q000494:pharmacology; D007457:Iodine Radioisotopes; D007536:Isomerism; D008297:Male; D010179:Pancreas / Q000378:metabolism; D017729:Presynaptic Terminals / Q000502:physiology*; D019275:Radiopharmaceuticals; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D014443:Tyrosine / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000493:pharmacokinetics / Q000652:urine
chemical_list: D004791:Enzyme Inhibitors; D006834:Hydrazines; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D014443:Tyrosine; C004297:3-hydroxybenzylhydrazine; C015566:3-tyrosine; D004298:Dopamine