FIGURE 15-36 Oscillations in the cytosolic Ca²⁺ concentration following treatment of human HeLa cells with histamine. Like the LH receptors described in the text, the histamine GPCR activates the IP₃-DAG signaling pathway. The feedback loops generating the spikes in the cytosolic Ca²⁺ concentration are detailed in the text.

[Data from A. Miyawaki et al., 1997, Nature 388:882.]