Effects of anoxia on kinetics of (/sup 13/N) glutamate and /sup 13/NH/sub 3/ metabolism in rabbit myocardium

Journal Article · Wed Apr 01 00:00:00 EST 1987 · Circ. Res.; (United States)

DOI:https://doi.org/10.1161/01.RES.60.4.505· OSTI ID:6068522

Krivokapich, J; Keen, R E; Phelps, M E; Shine, K I; Barrio, J R

Positron emission tomography is a unique noninvasive imaging technique that provides cross-sectional images of radiotracer concentrations in myocardium and permits measurement of blood flow as well as metabolism. Ammonia and glutamate have been labeled with the positron-emitter /sup 13/N (half-life 10 minutes) for use with positron emission tomography as tracers of flow and metabolism, respectively. In order to characterize the fate of these /sup 13/N-labelled compounds in myocardium, isolated rabbit interventricular septa were used to study the kinetics of (/sup 13/N) glutamate ((/sup 13/N)glu) and /sup 13/NH/sub 3/ under aerobic and anoxic conditions. Tissue analyses 6 minutes after injection of a (/sup 13/N)glu bolus into myocardium revealed that 70% of the /sup 13/N-label was present in (/sup 13/N)glu 12%, 11%, and 4% in (/sup 13/N)alanine ((/sup 13/N)ala), (/sup 13/N)aspartate ((/sup 13/N)asp), and (/sup 13/N)glutamine ((/sup 13/N)gln), respectively. The corresponding relative specific activities were 1.0:0.4:0.5:0.01. Anoxia resulted in a significant increase in (/sup 13/N)ala with a reduction in (/sup 13/N)glu. This was consistent with increased pyruvate production due to increased anaerobic glycolysis and transamination of pyruvate with (/sup 13/N)glu to yield (/sup 13/N)ala. In support of this, addition of 2 mM pyruvate to the perfusate under control conditions produced a tissue distribution of /sup 13/N similar to that with anoxia. Six minutes after a bolus of /sup 13/NH/sub 3/ during both control and anoxic conditions, 60% of the tissue /sup 13/N-label was in (/sup 13/N)gln with no detectable amounts in other amino acids. The rest of the /sup 13/N-label was in /sup 13/NH/sub 3/. Time-activity curve analyses demonstrated that anoxia significantly reduced the tissue retention of /sup 13/N-label from /sup 13/NH/sub 3/ but not from (/sup 13/N)glu.

• Research Organization: Univ. of California, Los Angeles, CA (United States)
• OSTI ID: 6068522
• Journal Information: Circ. Res.; (United States), Vol. 60:4
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
62 RADIOLOGY AND NUCLEAR MEDICINE
AMMONIA
METABOLISM
ANOXIA
BIOLOGICAL EFFECTS
GLUTAMIC ACID
MYOCARDIUM
BLOOD FLOW
BIOCHEMICAL REACTION KINETICS
COMPUTERIZED TOMOGRAPHY
LABELLED COMPOUNDS
NITROGEN 13
RABBITS
RETENTION
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
DIAGNOSTIC TECHNIQUES
ELECTRON CAPTURE RADIOISOTOPES
HEART
HYDRIDES
HYDROGEN COMPOUNDS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
MINUTES LIVING RADIOISOTOPES
MUSCLES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
RADIOISOTOPES
REACTION KINETICS
TOMOGRAPHY
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology
550601 - Medicine- Unsealed Radionuclides in Diagnostics