Figure 3. Neuronally-evoked astrocyte [Ca²⁺]_i rise depends on P2X₁ receptors.

(a) An astrocyte patch-loaded with AlexaFluor 594 (top) and Fluo4 (bottom) showing the processes, endfoot and soma. White dashed lines delineate the vessel lumen ensheathed by the endfoot process. (b) Neuronal stimulation evoked a [Ca²⁺]_i rise in astrocyte endfeet in control conditions (left); the rise was smaller in the presence of the P2X₁ blocker NF449 (100 nM, right). Arrow indicates a spontaneous Ca²⁺ transient, demonstrating that Fluo-4 could still detect [Ca²⁺]_i transients with NF449 present. (c) Mean change in neuronally-evoked astrocyte [Ca²⁺]_i in somata, processes and endfeet in the absence and presence of different blockers. NF449 (black bars), a blocker of P2X1 channels, significantly reduced the [Ca²⁺] rise in processes and endfeet, but S-MCPG, a blocker of groups I and II mGluRs had no effect on astrocyte [Ca²⁺] in any compartment (grey bars). Time to 10% of the peak and to the peak [Ca²⁺] change in endfeet were 5.27+1.15 s and 11.57+2.39 s respectively. Data are shown as box and whisker plots as defined in the Statistics part of the Methods.