Fig. 6.
(A) Blockade of Ca2-induced Ca2+ release from intracellular stores with ryanodine (10 μm, n = 17 neurons) minimally diminishes dimensions of the Ca2+ transient (indicated by fluorescence ratio R340/380) induced by K+ depolarization (50 mm;arrows). (B) Overload of Ca2+ stores only partially accounts for the sustained offset of the baseline R(340/380) after neuronal activation with K+ depolarization (arrow). Caffeine application (20 μm, n = 24 neurons) transiently elevates cytoplasmic Ca2+ concentration but does not return the resting level back to the original baseline (dotted line).