title: Determination of cerebral glucose transport and metabolic kinetics by dynamic MR spectroscopy.
abstract: A new in vivo nuclear magnetic resonance (NMR) spectroscopy method is introduced that dynamically measures cerebral utilization of magnetically labeled [1-13C]glucose from the change in total brain glucose signals on infusion. Kinetic equations are derived using a four-compartment model incorporating glucose transport and phosphorylation. Brain extract data show that the glucose 6-phosphate concentration is negligible relative to glucose, simplifying the kinetics to three compartments and allowing direct determination of the glucose-utilization half-life time [t1/2 = ln2/(k2 + k3)] from the time dependence of the NMR signal. Results on isofluorane (n = 5)- and halothane (n = 7)-anesthetized cats give a hyperglycemic t1/2 = 5.10 +/- 0.11 min-1 (SE). Using Michaelis-Menten kinetics and an assumed half-saturation constant Kt = 5 +/- 1 mM, we determined a maximal transport rate Tmax = 0.83 +/- 0.19 mumol.g-1.min-1, a cerebral metabolic rate of glucose CMRGlc = 0.22 +/- 0.03 mumol.g-1.min-1, and a normoglycemic cerebral influx rate CIRGlc = 0.37 +/- 0.05 mumol.g-1.min-1. Possible extension of this approach to positron emission tomography and proton NMR is discussed.
authors.affiliation: Johns Hopkins University Medical School, Department of Radiology, Baltimore 21205, USA.
authors.forename: P C
authors.initials: PC
authors.lastname: Van Zijl
authors.forename: D
authors.initials: D
authors.lastname: Davis
authors.forename: S M
authors.initials: SM
authors.lastname: Eleff
authors.forename: C T
authors.initials: CT
authors.lastname: Moonen
authors.forename: R J
authors.initials: RJ
authors.lastname: Parker
authors.forename: J M
authors.initials: JM
authors.lastname: Strong
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes; D002415:Cats; D005947:Glucose / Q000378:metabolism*; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006943:Hyperglycemia; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008959:Models, Neurological; D015203:Reproducibility of Results; D014055:Tomography, Emission-Computed
chemical_list: D002247:Carbon Isotopes; D019298:Glucose-6-Phosphate; D005947:Glucose