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Figure 1. Ca2+ oscillations induced by HlyA in IHKE cells loaded with the fluorescent Ca2+ indicator Fura-2/acetoxymethyl ester. A–D) Cells were exposed to HlyA (5 ng/ml) 3 min after start of recording. Traces represent examples of time courses of [Ca2+]i of 4 single cells. E) Single frames from an image series of [Ca2+]i. Frames 1–4 correspond to numbers 1–4 above trace in A. Traces in A and B were recorded from cells that are marked with A and B. F) Superposition of Ca2+ responses of 49 IHKE cells in the presence of nifedipine (100 µM). Application of HlyA (5 ng/ml) is indicated by arrow. Gap represents time when field of view was changed to an area that had not been UV irradiated before. G) Ca2+ tracing of a single IHKE cell on consecutive exposure to a nonhemolytic HlyA mutant (=nh HlyA, 25 ng/ml) and wild-type HlyA (2.5 ng/ml).
