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.
Tsukada
Y
Y
Institute of Life Science, Soka University, Hachioji, Tokyo, Japan.
Kanamatsu
T
T
Watanabe
H
H
Okamoto
K
K
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