Figure 9.

Individual mitochondria limit the Ca²⁺ excitability of astrocyte processes. Astrocytes in organotypic cultures of rat hippocampus were transfected with pKillerRed-mito (A, red) and the genetic Ca²⁺ indicator LCK-GCaMP5G (B, pseudocolor). Individual mitochondria were photo-ablated by exposure (2 s) to 405 nm laser light (white arrow). GCaMP fluorescence was monitored throughout the recording. Box-and-whisker plots depict amplitude (C, peak ΔF/F0), distance propagated (D, μm), and time constants (E, seconds) of individual Ca²⁺ transients before and after photo-ablation of individual mitochondria. Error bars indicate 5%–95% range. Shoulders of boxes indicate 25%–75% intervals. Median of data is highlighted by horizontal line. *p < 0.05 (by Mann–Whitney test). ***p < 0.0001 (Mann–Whitney test). n = 12 and n = 63 spikes before and after photoablation, respectively (7 cells).