In vivo investigation of glutamate-glutamine metabolism in hyperammonemic monkey brain using 13C-magnetic resonance spectroscopy.
To investigate the metabolism of glutamate and glutamine in living monkey brain, a system of in vivo 13C magnetic resonance spectroscopy (MRS) using 1H-decoupled 13C spectroscopy combined with monitoring temperature changes in the brain by MR phase mapping was developed. Serial 13C-NMR spectra of the amino acids glutamate and glutamine were acquired non-invasively over 4 h from anesthetized monkey brain after the intravenous administration of [1-13C]glucose (0.5-1.0 g/kg). In the acute hyperammonemic state induced by the administration of ammonium acetate (77 mg/kg bolus), it was observed that 13C incorporation into glutamine-4 was clearly accelerated, without changes of 13C incorporation into glutamate-4. During hyperammonemia, it was shown directly by [2-13C]glucose administration that the anaplerotic pathway for the TCA cycle was also augmented, contributing to the formation of glutamine in the astroglia.
Institute of Life Science, Soka University, Hachioji, Tokyo, Japan.
Y
Y
Tsukada
T
T
Kanamatsu
H
H
Watanabe
K
K
Okamoto
D000085:Acetates / Q000494:pharmacology; D000641:Ammonia / Q000097:blood*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes; D005260:Female; D005947:Glucose / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D008658:Inactivation, Metabolic / Q000502:physiology; D007275:Injections, Intravenous; D007536:Isomerism; D008252:Macaca fascicularis; D009682:Magnetic Resonance Spectroscopy; D008297:Male
D000085:Acetates; D002247:Carbon Isotopes; D005973:Glutamine; D018698:Glutamic Acid; D000641:Ammonia; D005947:Glucose; C018824:ammonium acetate