TY - JOUR
T1 - Oxidation of acetate in rabbit skeletal muscle
T2 - Detection by 13C NMR spectroscopy in vivo
AU - Szczepaniak, Lidia
AU - Babcock, Evelyn E.
AU - Malloy, Craig R.
AU - Sherry, A. Dean
PY - 1996/9
Y1 - 1996/9
N2 - The results of a proton-decoupled and Overhauser-enhanced 13C NMR study of acetate metabolism in skeletal muscle are reported. [2-13C]acetate was infused intravenously over 2 h into anesthetized rabbits, and skeletal muscle in the lateral thigh was monitored by 13C NMR spectroscopy at 4.7 T. Stable 13C enrichment in carbons 2, 3, and 4 of glutamate was observed at the end of the infusion, and the half-time for enrichment was 17 min for glutamate C4 and 50 min for glutamate C2 and C3. The contribution of exogenous acetate to acetylcoenzyme A was nearly equal in skeletal muscle and heart in vivo (83-87%, measured in tissue extracts), comparable with earlier perfused heart studies in which acetate was the sole available substrate. Although relative flux through the combined anaplerotic pathways (relative to citric acid cycle flux) was higher in quiescent skeletal muscle (26%) compared with hearts (3%) from the same animals, actual anaplerotic flux was estimated to be substantially higher in heart than in skeletal muscle after correcting for differences in citric acid cycle flux in the two tissues.
AB - The results of a proton-decoupled and Overhauser-enhanced 13C NMR study of acetate metabolism in skeletal muscle are reported. [2-13C]acetate was infused intravenously over 2 h into anesthetized rabbits, and skeletal muscle in the lateral thigh was monitored by 13C NMR spectroscopy at 4.7 T. Stable 13C enrichment in carbons 2, 3, and 4 of glutamate was observed at the end of the infusion, and the half-time for enrichment was 17 min for glutamate C4 and 50 min for glutamate C2 and C3. The contribution of exogenous acetate to acetylcoenzyme A was nearly equal in skeletal muscle and heart in vivo (83-87%, measured in tissue extracts), comparable with earlier perfused heart studies in which acetate was the sole available substrate. Although relative flux through the combined anaplerotic pathways (relative to citric acid cycle flux) was higher in quiescent skeletal muscle (26%) compared with hearts (3%) from the same animals, actual anaplerotic flux was estimated to be substantially higher in heart than in skeletal muscle after correcting for differences in citric acid cycle flux in the two tissues.
KW - C isotope tracer
KW - Krebs citric acid cycle
KW - NMR spectroscopy
KW - skeletal muscle metabolism
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U2 - 10.1002/mrm.1910360318
DO - 10.1002/mrm.1910360318
M3 - Article
C2 - 8875417
AN - SCOPUS:0029763251
SN - 0740-3194
VL - 36
SP - 451
EP - 457
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 3
ER -