Determination of cerebral glucose transport and metabolic
kinetics.
Zijl, P. C. M. Van, D. Davis, S. M. Eleff, C. T. W. Moonen, R. J.
Parker, and J. M. Strong.
Johns Hopkins University Medical School, Depts. of Radiology and
Anesthesiology, 217 Traylor Building, 720 Rutland Ave, Baltimore, MD
21205.National Institutes of Health, In vivo NMR Research Center,
BEIP, NCRR, Bethesda, MD 20892 & Resonance Magnetique des Systemes
Biologique, Universite Victor Segalen, F-33076 Bordeaux cedex, France
Food and Drug Administration, CDER/ORR, Div. of Clinical
Pharmacology, Rockville, MD 20850
APStracts 4:0194E, 1997.
A new in vivo NMR spectroscopy method is introduced that dynamically
measures cerebral utilization of magnetically labeled {1-13C}-glucose
from the change in total brain glucose signals upon 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 from
the time dependence of the NMR signal. Results on isofluorane- (n = 5
) and halothane- (n = 7) anesthetized cats give a hyperglycemic =
5.10 +/- 0.11 min-1 (S.E.M.). Using Michaelis Menten kinetics and an
assumed half-saturation constant = 5 +/- 1 mM, we determined a
maximal transport rate = 0.83 +/- 0.19 [mu]mol/g/min, a cerebral
metabolic rate of glucose = 0.22 +/- 0.03 [mu]mol/g/min and a
normoglycemic cerebral influx rate = 0.37 +/- 0.05 [mu]mol/g/min.
Possible extension of this approach to PET and proton NMR is
discussed.
Received 25 March 1997; accepted in final form 22 August 1997.
APS Manuscript Number E137-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 5 September 1997