Figure 3.

(A-B) Effects of an NMDA stimulation or a KCL and Saclofen infusion under normobaric (n = 8/9) and high (n = 6/9) nitrogen-oxygen pressure atmospheres on levels of extracellular citrulline (A) and arginine (B) in the rat striatum. A helium-oxygen (n = 8) mixture was used as the control in order to evaluate the effect of pressure per se, and it was compared to the nitrogen-oxygen (n = 6) mixture used in order to induce nitrogen narcosis (effect of narcosis and pressure are linked). The ordinate of each graph shows the median level of amino-acid expressed as the percentage of the baseline level, which is the mean of the four consecutive values observed immediately before the beginning of the compression/infusion of NMDA (2 mM) or KCl (100 mM) and Saclofen (1 mM). The time for compression (or simili) is shown by the grey area, which is followed by the maximum pressure period, 3 MPa (or simili). Dotted lines mark control experiments using helium at 3MPa or retrodialysis under atmospheric pressure. Lines mark experiments conducted in nitrogen at 3 MPa. Intergroup comparisons: strong signs in the corners of the graph indicate significant change in the evolution of citrulline or arginine levels (α = 0.05, Kruskal-Wallis test) between the nitrogen group and the NMDA-nitrogen group (#) or the KCl-Saclofen-nitrogen group (*). Small signs # and * at the corresponding time point indicate significant changes (α = 0.05, post hoc Dunn test) between the nitrogen group and the NMDA-nitrogen group (#) or the KCl-Saclofen-nitrogen group.