Fig. 3. The somatodendritic and axonal CXCR4 receptors are functionally coupled to intracellular Ca²⁺ mobilization. (A) Phase contrast and pseudocolour images of a field containing dendrites and axons. Neurons were loaded with Fura-2 AM and exposed to 20 nM SDF-1. Pseudocolour images were taken 5 seconds before SDF-1 stimulation (–5 sec), 7 seconds and 40 seconds after SDF-1 stimulation. Most processes displayed SDF-1-induced [Ca²⁺]_i increase. The colour calibration bar shows pseudocolour mapping of the ratio of fluorescence emission at 340 and 380 nm. (B) Higher magnification of the boxed regions shown in A show a dendrite and an axon based on morphological features analysed by phase-contrast microscopy. (C) Traces of variations of [Ca²⁺]_i recorded in the boxed regions depicted in A. A rise in [Ca²⁺]_i levels was observed with a similar time course for dendrites and axons, 3 seconds after SDF-1 exposure as symbolized by asterisks, and recovered to near basal levels within 1 minute. Bar, 10 µm.