Figure 5

ATP-induced [Ca²⁺] _i variations in differentiated GL15 cells. Panel A shows a single Ca²⁺ spike induced by 200 μM ATP (arrow) in 32% of differentiated cells (n = 69); addition of 2 μM thapsigargin (Tg) (arrow) evoked a further increase in [Ca²⁺]_i. In 18% (12 out of 69) of differentiated cells, 200 μM ATP (arrow) induced Ca²⁺ oscillations, partially inhibiting the thapsigargin-induced Ca²⁺ increase (B). Time (s=seconds) is indicated on the abscissa; the ordinate gives the normalized fluorescence value (f/f₀).