FIGURE 3.

Extracellular Ca²⁺ is not required for IP₃-induced Ca²⁺ oscillations. Isolated hepatocytes loaded with caged IP₃ and Fluo-4 were stimulated with 3 UV flashes (UV). A and B, representative traces of Ca²⁺ responses are shown in the presence (A) and absence (B) of extracellular Ca²⁺. C–E, summary of the Ca²⁺ signatures observed (C), oscillation frequency (D), and Ca²⁺ peak width at half-height (E) in the presence and absence of extracellular Ca²⁺. Data are mean ± S.E. of 25 cells from two independent experiments. *, p < 0.05, Student's t test.