Capa GPCR and NMUR in Fluid Homeostasis Figure 1. [Ca2+]i signatures in response to capa-1 and capa-2 in capaR- and apoaequorin-transfected S2 cells. (A) [Ca2+]i increases stimulated by 1027 M capa-1 (black) and capa-2 (grey). The traces shown are typical data from single experiments. Data are expressed as [Ca2+]i (nM) against time (s); each data point corresponds to 0.1 s; agonist injection indicated by an arrow. (B) Real-time measurement of the [Ca2+]i response to the capa peptides under Ca2+-free conditions. Data are expressed as [Ca2+]i (nM) against time (s); each data point corresponds to 0.1 s. The graphs display [Ca2+]i increases in capaR and apoaequorin expressing S2 cells. Traces shown are typical data from single experiments in response to 1027 M capa-1 (black) or capa-2 (grey) in the absence of Ca2+. In (A) and (B) the upward arrow indicate the time of peptide agonist injection while the downward arrows indicate the primary and secondary capa-induced calcium responses. (C) Dose-response curves for capa-1 and capa-2. Action of the capa peptides (capa-1 (black) or capa-2 (grey)) on S2 cells expressing capaR and apoaequorin. Values were expressed as maximal (nM) - background (nM) (mean 6 S.E.M., N = 6). Where error bars are not visible they are too small to reproduce. (D) Concentration-response for the action of the PLC inhibitor U73122. Cells were challenged with increasing concentrations of U73122, and calcium mobilization was measured. Values were expressed as maximal (nM) - background (nM) (mean 6 S.E.M., N = 3). doi:10.1371/journal.pone.0029897.g001 PLoS ONE | www.plosone.org 4 January 2012 | Volume 7 | Issue 1 | e29897