Fig 3. Beractant induces a reversible and concentration-dependent Ca2+ signal in NHLF.
Ca2+ response evoked in a single HNLF cell stimulated repeatedly with the same concentration of beractant (500 μg/ml), a reproducible cell-specific pattern of [Ca2+]i signal is observed in: A) a cell showing a rapid spike followed by a sustained plateau and B) in a cell showing a rapid spike followed by Ca2+ oscillations. C) A typical trace illustrating the increase in [Ca2+]i induced by beractant (0.1–500 μg/ml). D) Concentration-response relationship. The ΔR/Ri relationship is plotted against the logarithm of beractant concentration. Data points are means ± SE, n = 7–39 cells. The continuous curves were obtained by fitting the data to Eq 1, which yielded EC50 values of 0.8 μg/ml and 0.95 μg/ml for cells exhibiting either a single transient (closed symbols) or a sustained plateau (open symbols), respectively. R2 value for the curve fits were 0.9928 and 0.9890, respectively. Numbers into the graphics represent de beractant concentration in μg/ml.