Figure 1. Effects of Ca²⁺ depletion and blockers of Ca²⁺ entry on bradykinin-induced [Ca²⁺]_i rises in cultured mouse astrocytes.

Aa, bradykinin-induced rise in fura-2 ratio (F₃₄₀/F₃₈₀) in the cytoplasm averaged over 78 cells. Ab, bradykinin-induced F₃₄₀/F₃₈₀ rise in the absence of extracellular Ca²⁺ (n = 75). EGTA was not added in the bathing solution. Ac, bradykinin response in the absence of extracellular Ca²⁺ observed after pretreatment with 1 μm thapsigargin (Thap.) for 30 min (n = 69). Thapsigargin was included in the loading solution but not in the bathing solution. Ad, response in the presence of 1 μm Gd³⁺ (n = 90). Ae, response in the presence of 30 μm 2-APB (n = 85). Cells were preincubated in the Gd³⁺ or 2-APB containing solution for 10 min at room temperature before the measurements. Insets in Aa–e show typical F₃₄₀/F₃₈₀ traces observed in single cells for 15 min. All traces in this figure were recorded with a Roper NTE camera. B, comparison of the time integrals of net F₃₄₀/F₃₈₀ rises (areas in Δ(F₃₄₀/F₃₈₀) × seconds) from basal levels (indicated by dashed lines in Aa–e) over 1–15 min after the beginning of bradykinin application. The areas for comparison are indicated as shaded regions in Aa–e. All the areas except that in the control conditions (Aa) had negative values. This was presumably due to a temporary facilitating effect of bradykinin on Ca²⁺ extrusion (Ac). There are no statistical differences between these negative values (judged by multiple comparisons).