NO hyperpolarizes astrocytic mitochondria, but depolarizes neuronal
mitochondria. Cell suspensions (2 × 106 cells per ml)
were incubated at 37°C in buffered Hanks' solution either in the
absence (control) or presence of DETA-NO (0.5 mM) for the indicated
times. In this buffer, 0.5 mM DETA-NO was found to generate a constant
NO concentration of 1.4 μM. For Δψm measurements,
cell suspensions were centrifuged, and the pellet was resuspended in
buffered Hanks' solution containing JC-1 (3 μM) and incubated for a
further 10-min at 37°C. Data acquisition was performed in a
FACScalibur flow cytometer as detailed in Materials and
Methods. Data are expressed as a percentage, with the
red/green fluorescence ratio values of untreated cells
(2.98 ± 0.10 for neurons, 3.11 ± 0.20 for astrocytes)
considered as 100% and the red/green fluorescence ratio values
of FCCP (5 μM)-treated cells (0.68 ± 0.04 for neurons,
0.84 ± 0.05 for astrocytes) considered as 0%. *,
P < 0.05 versus appropriate control values.