Synthesis and myocardial kinetics of N-13 and C-11 labeled branched-chain l-amino acids

J. R. Barrio, F. J. Baumgartner, E. Henze, M. S. Stauber, J. E. Egbert, N. S. MacDonald, H. R. Schelbert, M. E. Phelps, Fu-Tong Liu

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26 Scopus citations


Glutamate dehydrogenase (GDH), immobilized on CNBr-activated Sepharose supports, was used with N-13 ammonia to aminate α-ketoisocaproic acid (KIC), and α-ketoisovaleric acid (KIV) to produce N-13-labeled branched-chain L-amino acids with radiochemical yields ranging from 29% to 35%. From kinetic and practical considerations, pH 7.5-8.0 was established to be optimal for the synthesis of N-13-labeled branched-chain-L-amino acids. Myocardial time-activity curves in dogs at control, during low-flow ischemia, reperfusion, and after transaminase inhibition following intracoronary bolus injection of the N-13-labeled amino acids were biexponential. Higher retention of N-13 activity was observed in ischemic segments both during low-flow ischemia (29.2%) and reperfusion (23.2%) when compared with controls (20.0%), (n = 4). On the other hand, transaminase inhibition decreased residue fractions from 21.0% at control to 13.9% (n = 4). The residual activity with L-[1-11C]leucine allows for the calculation of protein synthesis rates.

Original languageEnglish (US)
Pages (from-to)937-944
Number of pages8
JournalJournal of Nuclear Medicine
Issue number10
StatePublished - 1983
Externally publishedYes

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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