Figure 3. A correlation of k_io with ^tMR_O2.

Independent [K_o⁺] titrations of paramagnetic agent-superfused [SS-NMR] studies of organotypic, cultured [spiking] rat somatosensory cortex [ordinate] and direct studies of isolated rat brain synaptosome suspensions [abscissa] allow correlation of the population-averaged 〈k_io〉_n and 〈^tMR_O2〉_n quantities, respectively. The outer [K_o⁺] scales are non-linearly related to the linear, inner 〈k_io〉_n and 〈^tMR_O2〉_n scales due to their Michaelis-Menten relationships. The correlation of 〈k_io〉_n and 〈^tMR_O2〉_n is very strong. The SS-NMR studies also indicate the mean cell volume 〈V〉_n is rather constant. Thus, 〈k_ioV〉_n = 〈^cMR_AWC〉_n (pL(H₂O_i)/s/cell) correlates with 〈^tMR_O2〉_n (pmole(O₂)/s/mL(suspension)). (This is a combination of Figures 3C and 3E of reference (31), where details are provided. The points are synaptosome measurements: the dashed line is the Michaelis-Menten fitting (K_m = 4.5 mM) of the cortical culture measurements.)