A) Peptide release from spinal cord slices stimulated by three 10 minute exposures to HEPES buffer alone (open bars) or HEPES buffer containing 500 nM capsaicin (dark bars) is expressed as mean percent total peptide content of iCGRP in the spinal cord slice ± SEM (n = 3-10 animals per condition). GDNF, neurturin (NTN), or artemin (ART), at 10 ng/mL, was included in the six 10 minute incubations indicated by lines with growth factor name below, for a total exposure time of 60 min. B) Evoked release, or release due to capsaicin stimulation alone, is compared between growth factor treatment and no GFL groups. The evoked release was obtained by subtracting peptide release during the three basal fractions from that during the three capsaicin-stimulated fractions in each treatment group. Asterisks (*) indicate statistically significant differences in iCGRP release between treatment groups and the no growth factor condition using an ANOVA with Dunnett's post-hoc test (p<0.05). In all cases, release stimulated by capsaicin was significantly higher than basal release.