Fig. 2.
From: Relationship between oxygen consumption and neuronal activity in a defined neural circuit
Influence of bath O2 concentrations on ventricular O2 levels. a Recording of O2 levels in the bath and ventricle following stepwise increase of the bath O2 concentration from ~ 290 μmol/l (air-saturated) to ~ 550 μmol/l (light gray area), ~ 750 μmol/l (gray area), and ~ 950 μmol/l (dark gray area); the O2-electrode was initially advanced to the ventricular floor in 0.2 mm steps (left in a) and transiently repositioned to 1.2 mm above the floor (*) prior to each increase of the bath O2 concentration. b O2 concentration profiles (mean ± SEM) of ventricular depth tracks (see insets) in air-saturated (~ 290 μmol/l) bath solution (1; N = 31) and after the increase of the bath O2 concentration to ~ 550 μmol/l (2; N = 6), ~ 750 μmol/l (3; N = 6), and ~ 950 μmol/l (4; N = 6). c Scatter plot, depicting the dependency of the ventricular O2 concentration (black and red dots; n = 97 from 24 preparations) and adjacent hindbrain (blue dots; n = 69 from 11 preparations) from bath O2 levels; red dots represent the mean ± SEM of the ventricular O2 level at distinct bath O2 concentrations and the red dashed lines linear regressions through the lower (r2 = 0.98) and higher (r2 = 0.96) range of mean ventricular concentrations, respectively. d, e Scatter plot (d) and boxplot (e) depicting ventricular O2 consumption as function of the bath O2 level for concentrations > 700 μmol/l (n = 90 from 13 preparations) with a mean ± SEM of 626 ± 13 μmol/l (e); the slope of the regression line in d (r2 = 0.007) is not significantly different from zero (p = 0.42). O2 levels in a and b are color-coded from blue (0 μmol/l) to red (300 μmol/l) to yellow (600 μmol/l) to green (750 μmol/l) to cyan (900 μmol/l); transverse hindbrain schemes indicate motion (a) or position (b, c) of the O2 electrode. N, number of preparations; n, number of measurements