Table 2.
Ligand | cAMP | Arrestin | ||||
---|---|---|---|---|---|---|
Emax NFU | Emax % vaso | − log L50 (L50, nM) | Emax NFU | Emax % vaso | − log L50 (L50, nM) | |
Vasopressin | 0.51 ± 0.09a | 100 ± 0 | 10.05 ± 0.08b (0.089) | 0.16 ± 0.02c | 100 ± 0 | 7.68 ± 0.04d (21) |
Oxytocin | 0.56 ± 0.12a | 110 ± 5 | 9.44 ± 0.13b (0.36) | 0.16 ± 0.03c | 97 ± 4 | 6.75 ± 0.08d (180) |
The responses at a single time point (18 min after ligand application, 22 min after experiment initiation) were measured using genetically-encoded biosensors26,82 as described in Methods. See Fig. 6 for raw data. The data were fit to a sigmoid curve equation83 to determine the maximal initial rate (IRmax, the upper plateau, equivalent to kτ) and L50 (concentration of ligand giving an initial rate 50% of IRmax). Data values are mean ± SEM, n = 3. Curve fit results for each experiment are provided in the “Curve fit results” Supplementary file. NFU is normalized fluorescence units. Ligand parameters were compared statistically by paired two-tailed t-test, with the following p values: a0.258, b0.0496, c0.390, d0.0101.