Fig. 1B. Depolarization- and caffeine but not cADPR-evoked [Ca²⁺_c] increases in myocytes. (Ba) Depolarization (iv) activated I_Ca (iii) and increased [Ca²⁺]_c (i,ii). (i) Images of the [Ca²⁺]_c changes occurring throughout the cell before (A), during (B,C) and after (D-F) the depolarization, the times indicated by their respective letters above the plot of [Ca²⁺]_c against time in (ii). The changes in fluorescence ratio (F/F₀) with time (ii) are again from 1-pixel-wide lines (536 nm) across the cell at 10µm intervals. The positions of the lines are indicated in (Bbi) right-hand panel; the lines drawn are wider than 1 pixel to facilitate visualization. A bright field image of the cell and position of the patch pipette is shown (Bbi, left-hand panel). (Bb) cADPR ( 50 µM) did not increase [Ca²⁺]_c. (Bc) caffeine (CAF 10 mM, v) remained effective in this respect. The delay in onset of the caffeine response probably reflects the time required for the concentration of caffeine to build up between the puffer pipette and the cell.