FIG. 7.
A rapid mitochondrial response with no detectable oxidant burst is observed in irradiated BPAEC. Panel A: BPAEC cultured in 20% oxygen, preincubated with dihydrorhodamine 123 and assayed after irradiation showed no oxidant burst. Panel B: Incubation of irradiated BPAEC (10 Gy, ■) with DAF-2 resulted in a small NO increase shortly after irradiation compared to control (●); P < 0.05 (*). Inset: Differences in DAF-2 fluorescence between the results for irradiated and control cells were plotted as a cubic spline calculated to pass through the data. Panel C: Calcium fluxes after irradiation of BPAEC. Within 1 min, irradiation of cells loaded with the Ca2+ indicator dye Rhod-2 AM (2 μM) exhibited an increase in fluorescence indicating an increase in cytosolic calcium levels (dashed line) compared to control (solid line). After preloading of the cells with Rhod-2 for 24 h and subsequent irradiation, a weaker and transient calcium flux was detected (dotted line). Panel D: Changes in mitochondrial membrane polarization as measured by JC-1 30 min after irradiation (solid bars). Cells that overexpress MnSOD (crosshatched bars) are protected against membrane depolarization.