In vivo monitoring of hepatic glutathione in anesthetized rats by 13C NMR.
A method for in vivo (13)C NMR monitoring of hepatic glutathione (GSH) in intact, anesthetized rats has been developed. Studies were conducted using a triple-tuned, surgically implanted surface coil designed for this animal model. The coil permitted complete decoupling and sufficient resolution in the (13)C NMR spectrum to monitor the time course of hepatic (13)C-metabolites of intravenously administered 2-(13)C-glycine, particularly GSH at 44.2 ppm and serine signals at 61.1 and 57.2 ppm, respectively. It further allowed concomitant monitoring of high-energy phosphagens and intracellular pH by (31)P NMR. To confirm in vivo NMR peak assignments, we compared high-resolution 2D (1)H[(13)C] heteronuclear multiple quantum coherence and 1D (13)C spectra of hepatic perchloric acid extracts to those of authentic standards. The fractional isotopic enrichment of hepatic (13)C-glycine increased exponentially at a rate of 1.68 h(-1) and reached its plateau level of 81% in 2 h. The (13)C fractional isotopic enrichment of GSH increased exponentially at a rate of 0.316 h(-1) and reached 55% after 4 h of 2-(13)C-glycine infusion, but without achieving a plateau. To confirm that the resonance at 44.2 ppm resulted from GSH, a rat was given an intravenous dose of 2-oxothiazolidine-4-carboxylic acid (OTC), a cysteine precursor that increases intracellular GSH. As expected, with OTC administration the hepatic (13)C GSH-to-glycine peak area increased more than sevenfold.
Macdonald
Jeffrey M
JM
Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, California 94143, USA.
Schmidlin
Olga
O
James
Thomas L
TL
D000818:Animals; D002247:Carbon Isotopes; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D005998:Glycine; D008099:Liver / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D011761:Pyrrolidonecarboxylic Acid; D051381:Rats; D017207:Rats, Sprague-Dawley; D013844:Thiazoles; D053778:Thiazolidines
D002247:Carbon Isotopes; D013844:Thiazoles; D053778:Thiazolidines; D005978:Glutathione; D011761:Pyrrolidonecarboxylic Acid; D005998:Glycine; C029536:2-oxothiazolidine-4-carboxylic acid