Figure 1.

Effects of bombesin, neuromedin B, bradykinin, cholecystokinin and serum on [Ca²⁺]_i in SCLC cell lines GLC14, GLC16 and GLC19. Cells loaded with FURA-2-AME were resuspended in electrolyte solution and placed in a quartz cuvette. Fluorescence was monitored and basal and peak [Ca²⁺]_i calculated as described in Materials and Methods. Panel A: All peptides were added at a final concentration of 100 nM. Abbreviations used: BN, bombesin; NmB, neuromedin B; BK, bradykinin; CCK, cholecystokinin. Serum was added at a final concentration of 1% v v⁻¹. Panel B: Dose-dependent effects of bombesin, neuromedin B, bradykinin and CCK in SCLC cell lines GLC16 and GLC19, open and closed circles, respectively. Peptides were added at the concentrations indicated. Representative concentration–response relations of three to five experiments are shown. Panel C: mRNA encoding the GRP receptor was detected by semiquantitative RT–PCR. γ-Actin mRNA levels were measured as an internal control for each PCR reaction. The results show a representative PCR reaction for the GLC14,16 and 19 cell lines. A bar chart showing relative receptor expression, calculated as density of PCR product/actin is shown for each cell line. The results represent the mean of two independent experiments.