Figure 2. Representative different calcium responses of HCECs to PAF. PAF (10 nM) was added at 0 min. The y-axis shows the intensity ratio of fluorescence at the two excitation wavelengths of a single cell. High ratio indicates higher [Ca²⁺]_i. A depicts a minimal response of a cell to PAF. B shows a rapid response to PAF followed by a relatively rapid decay of the [Ca²⁺]_i mobilization response. C displays a PAF-induced [Ca²⁺]_i mobilization response that lasts for at least 16 min. D shows an apparent oscillatory [Ca²⁺]_i mobilization pattern in an HCEC. The basal control effects with just the vehicle resembled the lack of response in A.