Synthesis and myocardial kinetics of N-13 and C-11 labeled branched-chain L-amino acids. [Dogs]
Glutamate dehydrogenase (GDH), immobilized on CNBr-activated Sepharose supports, was used with N-13 ammonia to aminate ..cap alpha..-ketoisocaproic acid (KIC), and ..cap alpha..-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 cosiderations, pH 7.5 to 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-/sup 11/C)leucine allows for the calculation of protein synthesis rates.
- Research Organization:
- Univ. of California, Los Angeles; Scripps Clinic and Research Foundation, La Jolla, CA
- OSTI ID:
- 5009979
- Journal Information:
- J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 24:10; ISSN JNMEA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINATION
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
BODY
CARBON 11
CARBON ISOTOPES
CARBOXYLIC ACIDS
CARDIOVASCULAR DISEASES
CARDIOVASCULAR SYSTEM
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISTRY
DECARBOXYLATION
DISEASES
DOGS
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
EVEN-ODD NUCLEI
HEART
ISCHEMIA
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIGHT NUCLEI
MAMMALS
METABOLISM
MINUTES LIVING RADIOISOTOPES
MUSCLES
MYOCARDIUM
NITROGEN 13
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOCHEMISTRY
RADIOISOTOPES
RADIOPHARMACEUTICALS
REACTION KINETICS
SYNTHESIS
VASCULAR DISEASES
VERTEBRATES