Figure 4.

Peroxynitrite is highly toxic to astrocytes. (a) Fluorescence images of astrocytes loaded with the ONOO^– sensitive dye, 2-[6-(4′-amino) phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (APF). Cells were first treated with vehicle (DMSO; 1:1000) and then SNAP (200 μM) alone or together with pyrogallol (100 μM). (b) Example timecourses of the changes in APF fluorescence seen in cells exposed to SNAP alone (10 μM) or SNAP together with pyrogallol (100 μM). (c) Mean±S.E.M. peak fluorescence detected in astrocytes exposed to vehicle, SNAP (200 μM), SNAP together with pyrogallol (100 μM) or both agents together with the ONOO^– scavenger FeTPPS (50 μM). **P<0.01 as compared with control. (d) Effect on cell viability of a 24 h exposure of astrocytes to SNAP (200 μM), SNAP together with pyrogallol (100 μM) or both agents together with the antioxidant MnTMPyP (100 μM). Each bar represents the mean±S.E.M. taken from between 4 and 8 observations. Significance; ***P<0.001 as compared with control