Figure 6.
Modeling the O2 consumption of the slice. A, [O2] profile across the unstimulated slice in the stratum radiatum and stratum pyramidale (N = 6 slices). The slice surface is denoted position 0. B, Mean of data in the two regions in A (circles), and theoretical fits for different assumed Vmax values for O2 consumption (given by each curve), constrained to have the value 387 μm at x = 0. The best fit (in red) is with Vmax = 0.7 mm/min. C, Fitting the [O2] decrease evoked by stimulation at a position 92 μm into the slice. Black circles are the mean control data in 95% O2 from Figure 3B. Each smooth curve is the computed response to an increase of Vmax from 0.7 to 1.5 mm/min, followed by a decay back to 0.7 mm/min with the rate constant (in min−1) shown by each curve. The best fit (red) is with a rate constant of 2.5 min−1, i.e., a time constant of 0.4 min or 24 s. D, Predicted [O2] profiles across the slice in the resting state and at the peak of the O2 dip following stimulation. E, Predicted dependence of the amplitude of the [O2] transient on the underlying increase of the Vmax for O2 use. F, Predicted relationship between the increase in O2 consumed at the recording site and the size of the O2 dip (the curve is O2 consumption/mm = 7.8 × (oxygen dip/mm)1.3).