Table 2.
Increasing impulse frequency within bursts increases the effectiveness of proctolin at enhancing nerve-evoked contractions
| Intraburst Impulse Rate, Hz | No. of Impulses | Threshold | EC50 |
|---|---|---|---|
| 2 | 1 | 10−10–10−9 M | 8.4 × 10−8 M |
| 5 | 2 | 10−10–10−9 M | 4.0 × 10−8 M |
| 10 | 3 | 10−11–10−10 M | 1.8 × 10−8 M |
| 20 | 6 | 10−11–10−10 M | 4.6 × 10−9 M |
| 32 | 9 | 10−12–10−11 M | 1.7 × 10−9 M |
A dose-response curve was generated for the 5 listed stimulus rates. Both the threshold for enhancement of contractions and the EC50 values for proctolin decreased with increases in intraburst stimulus rate.