Selective, in vivo observation of [5-15N]glutamine amide protons in rat brain by 1H-15N heteronuclear multiple-quantum-coherence transfer NMR.
The amide protons of [5-15N]glutamine were selectively observed in vivo in the brains of anesthetized, spontaneously breathing rats after intravenous 15NH4+ infusion by 1H-15N heteronuclear multiple-quantum-coherence (HMQC) transfer NMR at 200 MHz for 1H. The peak intensity of the upfield amide proton was proportional to brain [5-15N]glutamine concentration. The 15N-decoupled amide-proton signal was observed in vivo in 2 min of acquisition at a brain [5-15N]glutamine concentration of 7.7 +/- 0.4 mumol/g, in < 8 min at 4.35 +/- 0.15 mumol/g, and in 17-34 min at 2.0 +/- 0.1 mumol/g. 1H signals not coupled to 15N were suppressed by phase cycling. The result suggests that 1H-15N HMQC will be useful for kinetic study of glutamine synthesis in rat brain in vivo at physiological concentrations of brain ammonia.
Kanamori
K
K
Huntington Medical Research Institutes, Pasadena, California 91105, USA.
Ross
B D
BD
Tropp
J
J
D000577:Amides / Q000737:chemistry*; D000818:Animals; D001923:Brain Chemistry; D005973:Glutamine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009587:Nitrogen Isotopes; D011522:Protons; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar
D000577:Amides; D009587:Nitrogen Isotopes; D011522:Protons; D000644:Quaternary Ammonium Compounds; D005973:Glutamine