Fig. 3

Application of CGRP to Xenopus laevis oocytes expressing CGRP-R, AMY₁-R and CTR caused a concentration-dependent increase in current at a holding potential of − 70 mV with CGRP being most potent on CGRP-R before the AMY₁-R and CTR. CGRP had no effect on oocytes expressing RAMP1, CLR or non-injected oocytes (control). Curve fittings by non-linear regression curves using least square non-lin fit of the c-r relationship of log(agonist) vs. response (three parameters) were performed. The top and the bottom of the curves were constrained to the maximum response of CGRP and zero, respectively for CGRP-R, AMY₁-R and CTR. Furthermore, the response to 3 μM of CGRP at the CGRP-R was not included in the calculation of the non-linear regression curve (indicated by dashed line) Statistical evaluation was performed by ordinary One-way ANOVA followed by Dunnet’s multiple comparisons test on the response to the different concentrations of CGRP at each receptor as compared to the 1 μM CGRP response in non-injected control oocytes * p < 0.05; **p < 0.01. The number of experiments performed at each data point is between 2 and 15. Each curve-fitting relies on experiments performed on 13 non-injected oocytes, and 36, 30, 20, 14 and 27 oocytes expressing CGRP-R, AMY₁-R, RAMP1, CLR and CTR, respectively