FIGURE 6.

Reducing the Ca²⁺ content of the stores prior to stimulation reduces the rundown of Ca²⁺ oscillations in caveolin-1-GFP (Cav1)- expressing cells. A, preincubation in Ca²⁺-free solution reduces the store Ca²⁺ content, as assessed by the extent of Ca²⁺ release to thapsigargin. The black trace is control (∼30 s in Ca²⁺-free solution). The dotted trace is the response after 10 min in Ca²⁺-free solution. Each trace represents the average of 15–35 cells from four independent experiments. B, same as in A, but for cells expressing caveolin-1. C, aggregate data from several recordings as in A and B are summarized. D, typical oscillatory responses to LTC₄ obtained in Ca²⁺-free solution containing La³⁺. In each of the panels D–G, two cells (solid line and dotted line) treated the same way but from two different preparations are shown. E, typical oscillatory responses after preincubation in Ca²⁺-free solution for 10 min. F, oscillatory responses to LTC₄ in cells expressing caveolin-1. G, oscillatory responses to LTC₄ in caveolin-1-expressing cells after pre-exposure to Ca²⁺-free solution for 10 min. H, the amplitude of the first oscillation for each condition is shown. I, the average numbers of oscillations obtained over 600 s for each condition are compared. Each bar represents between 15–38 cells from three independent experiments. **, p < 0.01; ***, p < 0.001.