Figure 5. ROS generation during the pH_o-conditioned current.

The images in A and B represent the bright fields and dihydroethidium (DHE) fluorescence images of 2 different cultures of nodose neurons. (A) The cells were observed for up to 30 minutes after DHE loading in a bath solution at pH_o 7.4, without exposing them to low pH_o 6.0 (control). (B) The cells were loaded with DHE and then exposed transiently to pH_o 6.0. The middle image shows minimal fluorescence before exposure to pH_o 6.0, and the right image shows pronounced fluorescence approximately 10 minutes after exposure to pH_o 6.0. The corresponding graphs (C and D) show that after loading with DHE (large black arrows); the slope of spontaneous fluorescence seen over 30 minutes without exposure to low pH_o is minimal in C (control cells) as reflected in the third fluorescence image in A. (D) The slope is dramatically increased following the 3 transient exposures to pH_o 6.0 (small red arrows) as reflected in fluorescence image in B. The dot plot shows the slopes of fluorescence of individual neurons averaging 0.04 ± 0.01 units/min before and 0.12 ± 0.02 units/min after exposure to low pH_o (n = 31 neurons from 2 mice, **P < 0.01 compared with before exposure). Statistical comparison is a paired 2-tailed Student’s t test.