FIGURE 1.

Heterogeneity in the Ca²⁺ response elicited by histamine in WI-38 human lung fibroblasts. Application of histamine (300 μM) elicited different Ca²⁺ signal patterns in FURA-2 AM-loaded WI-38 human lung fibroblasts. The intracellular Ca²⁺ signal consisted of (A) a rapid Ca²⁺ peak (spike) (19.28% of cells analyzed) which could be followed by (B) Ca²⁺ oscillations (64.70%) (peak-oscillations), (C) sustained plateau, superimposed by Ca²⁺ oscillations (13.39%) (peak-plateau-oscillations) or (D) only a plateau (0.65%) (peak-plateau). In this and the following figures, histamine was added at the time indicated by the horizontal bar drawn over the Ca²⁺ signal recording.