Figure 2.

(a) Comparison of the amount of [Ca²⁺]_i changes between ATP_o (arrows: 50 μM, 20 s)-induced [Ca²⁺]_i increase and decrease (see text for details). (b) Inhibition of ATP_o-induced decrease in [Ca²⁺]_i by 2 mM orthovanadate. Cells were incubated in culture medium containing 200 nM TG during 30-min Fluo-3 loading before rinsing with the Ca²⁺-free solution. [Ca²⁺]_i was elevated with the standard solution containing 1.3 mM Ca²⁺ like that in (a). ATP_o (arrows: 50 μM, 20 s) was applied to the cells once the [Ca²⁺]_i had reached a steady-state level.