FIGURE 3.

Effect of Ca²⁺-free and Ca²⁺-confining solutions on response to 5 mM caffeine. (A) Peak and plateau values in response to 30-s CAF stimulation, in Ca²⁺-free medium (open columns, n = 21) and Ca²⁺-confining medium (shaded columns, n = 11). (B) Original trace of Ca²⁺ response to two successive stimulations by CAF for 1 s, at a 15-s interval in the presence of external Ca²⁺ (left), in Ca²⁺-free medium (middle), and in Ca²⁺-confining solution (right). (C) Left panel, mean values of the Ca²⁺ response to two successive stimulations by CAF for 1 s, at a 15-s interval in Ca²⁺-free medium (open columns, n = 13) and Ca²⁺-confining solution (shaded columns, n = 23). (C) Right panel, mean [Ca²⁺]_i decay after the first CAF-induced peak in control (•, n = 22) and Ca²⁺-confining solution (○, n = 23), as percentage of the control peak, 0 corresponding to baseline. Vertical bars are SE.