Figure 3

ATP-induced Ca²⁺ mobilization in the nucleus and cytoplasm of mouse granulosa cells. Cells were incubated with Fluo-4 AM (5 μM) and analyzed by confocal microscopy. Each image represents the temporal changes in [Ca²⁺]i of a set of nearly 200 granulosa cells. Plots in the left column show the temporal pattern of fluorescent fluctuations of each experiment. Images were acquired every second, and the signals are expressed in arbitrary fluorescent units (AFU). N = nucleus and C = cytoplasm. The period of ATP (50 μM) delivery is indicated in the black box, whereas application of xestospongin C (Xes) (5 μM for 15 min) and brefeldin A (Bf A) (5 μg/ml for 2 h) is depicted in white boxes. Greek letters represent Ca²⁺ mobilization before (α), during (β), and after (γ) ATP application. In the plot, light symbols indicate the temporal pattern of Ca²⁺ mobilization within the nucleus, whereas dark symbols correspond to the variation of cytoplasmic Ca²⁺. First block: Representative experiment of Ca²⁺ mobilization by ATP. Second and third blocks: Inhibitory action of pre-treatment with xestospongin C and brefeldin A on the nuclear and cytoplasmic ATP-induced Ca²⁺ mobilization. Representative of 4 independent experiments.