Blood-brain transport and metabolic rate of glucose measured with [11C]O-methyl-D-glucose (OMG)


Blood-brain transport and metabolic rate of glucose measured with [11C]O-methyl-D-glucose (OMG)

Kuwabara, H.; Brust, P.; Steinbach, J.; Bergmann, R.

OBJECTIVES: We used OMG, a specific tracer of glucose transport, to characterize blood-brain glucose transport independent of plasma glucose levels and to measure cerebral metabolic rate of glucose (CMRglc.).
METHODS: 17 young pigs were studied with PET for one hour following an i.v. injection of OMG and for one hour after i.v. FDG. Plasma glucose level was maintained relatively constant throughout scans with or without s.c. insulin or i.v. glucose infusion (range: 0.7-17.1 µM). In OMG studies, the unidirectional blood-to-brain and brain-to-blood clearances of OMG, K1* and k2* were estimated. K1* was related to plasma glucose level (Cp) as given by: K1* = Tmax*/(Kt*+Cp) (Eq.1), where Tmax* is the maximal transport and Kt* the half-saturation constant of OMG. CMRglc was given by: (k2*-K1*).Kt*.Tau (Eq.2) where Tau is the transport ratio (K1*/K1 of glucose). The equation was derived from an alternative definition of CMRglc: K1.Cp - k2.Me, where Me is the concentration of glucose in brain extra-cellular space. K1 and k2 of glucose were replaced by K1*/Tau and k2*/tau, and Me by the following equation: K1*/k2*=(Kt+Me)/(Kt+Cp). In FDG studies, the phosphorylation constant, k3*, was also estimated, and CMRglc was given by: K*.Cp/Lambda (Eq.3), where K* is K1*.k3*/(k2*+k3*), and Lambda the lumped constant (0.48).
RESULTS: Estimates of Tmax* and Kt* were 0.80 µmol/100g/min and 7.2 µM. The value of Tau which minimized CMRglc values of Eq.2 and 3 was 0.3. Despite wide variations of K1* and k2* estimates (ranges: 0.041-0.12 ml/g/min, 0.14-0.23 per min), CMRglc values by OMG (Eq.2) varied little (25.4±3.8 µmol/100g/min). CMRglc by FDG averaged 24.5±6.4 µmol/100g/min.
CONCLUSION: We characterized blood-brain glucose transport for pigs, and

  • Lecture (Conference)
    46th Annual Meeting of the Society of Nuclear Medicine, Los Angeles, 06.-10.06.1999
  • Abstract in refereed journal
    J. Nucl. Med. 40 (5) (1999) 73P

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Publ.-Id: 3072