In the results reported by Duarte et al. (see Figure 3 in [341]) using rats, following a step change in cplasma from 4 to 20 mM the brain content of glucose increased from about 0.5 to 4.5 µmol g−1 with a half life of about 16 min which indicates a net rate of accumulation of 0.122 µmol g−1 min−1, i.e. using their value of CMRglc, 0.52 µmol g−1 min−1, there is an influx of 0.64 µmol g−1 min−1 which is similar to that reported by Betz et al. in 1974 [302] for the dog.