Figure 4.

Independence of cellular Na⁺ and pH responses to glutamate. a, Glutamate-evoked cellular Na⁺ responses without concomitant pH changes. After a first control pulse of glutamate application, glutamate was superfused together with 6 mm TREA, the concentration found to compensate glutamate-induced cytosolic acidification. pH measurements in the cytosol (pH_cyt; n = 4, 32 cells) and mitochondrial matrix (pH_mit; n = 6, 20 cells) and Na⁺ measurements in the cytosol (Na_cyt⁺; n = 4, 30 cells) and mitochondria (Na_mit⁺; n = 4, 32 cells) were taken after 1.5 min of stimulation. Data are presented as means ± SEM. b, Cytosolic pH measurement during a pulse of 200 μm glutamate (solid line) and during glutamate plus TREA application (dotted line). In the example shown, 10.7 mm TREA effectively prevented the acidification during glutamate application, as measured after 5 min of glutamate application.