Figure 4.

(A) CMR_glc contour plot, assuming a glucose arterial plasma concentration equal to 500μmol/100 mL, a mean glucose concentration in the tissue under baseline condition equal to 129μmol/100 mL, and Michaelis-Menten parameters for transport of glucose v_{max_t} and K_T equal to 68μmol/100 mL/min and 50μmol/100 mL, respectively. (B) CMRO₂ contour plot (Angleys et al., 2015) assuming oxygen metabolism to be governed by Michaelis-Menten kinetics, with parameters K_M = 2.71mmHg (3.5 μmol/L) and v_max = 4.75 mL/100 mL/min. (C) CMRO₂ contour plot assuming v_max = 5.23 mL/100 mL/min [i.e., 10% higher than in (B)] and making otherwise the same assumptions as in (B). The parameter v_max in (B,C) is assumed to be constant. The yellow line separates states where a blood flow increase (decrease in MTT) given a fixed CTH will lead to an increased (right side of the line) or decreased (left side of the line) glucose (A) or oxygen (B,C) consumption, respectively. The roman numeral accompanying each symbol corresponds to physiological data. The numeral “0” stands for resting state, whereas other numerals refer to state of altered basal physiology. Note that the CMR_glc and CMRO₂ iso-contours do not show the same slope for the experimental data used in this figure, indicating that a change in MTT (resp. CTH) will have a strong (resp. moderate) influence on CMR_glc, and inversely for CMRO₂. Symbols: +, functional activation (Stefanovic et al., 2008); ×, cortical electrical stimulation (Schulte et al., 2003).