Table 1.
Fits of dose–response data with empirical Hill equations
| Chronic exposure to | High-affinity state | Low-affinity state | Imax pA | ||||
|---|---|---|---|---|---|---|---|
| (a1) | EC50H (μm) | nH1 | (1 − a1) | EC50L (μm) | nH2 | ||
| Control (59) | 25 ± 1 | 1.5 ± 0.1 | 0.93 ± 0.01 | 75 | 61 ± 0.8 | 1.5 ± 0.04 | 2202 ± 273 |
| 8–10 hr 100 nm (−)-nicotine (8) | 44 ± 5 | 1.4 ± 0.1 | 0.94 ± 0.03 | 56 | 61 | 1.5 | 3305 ± 448 |
| 19–23 hr 1 μm (−)-nicotine (5) | 45 ± 5 | 2.1 ± 0.4 | 0.90 ± 0.03 | 55 | 61 | 1.5 | 4798 ± 606 |
| 19–23 hr 10 μm (−)-nicotine (7) | 37 ± 6 | 1.4 ± 0.1 | 0.84 ± 0.03 | 63 | 61 | 1.5 | 3477 ± 341 |
| 8–10 hr 10 nm DHβE (7) | 50 ± 6 | 1.1 ± 0.2 | 0.84 ± 0.03 | 50 | 61 | 1.5 | 4868 ± 878 |
| 8–24 hr 10 μm DHβE (16) | 70 ± 5 | 0.67 ± 0.2 | 0.91 ± 0.06 | 30 | 61 | 1.5 | 6026 ± 539 |
| 8–10 hr 10 μm MLA (12) | 57 ± 3 | 1.6 ± 0.2 | 0.97 ± 0.02 | 43 | 61 | 1.5 | 5326 ± 735 |
| 10–24 hr 20 μm cyclo control (10) | 36 ± 3 | 1.5 ± 0.2 | 0.92 ± 0.04 | 64 | 61 | 1.5 | 3563 ± 645 |
| 10–24 hr 20 μm cyclo + DHβE 10 μm (11) | 54 ± 3 | 0.9 ± 0.1 | 1 ± 0.05 | 46 | 61 | 1.5 | 6012 ± 515 |
Control cells, recorded alternately with cells chronically exposed to drugs, were pooled together because they presented few variations between experiments. Data points of the dose–response values measured for cells exposed to drugs were fitted as follows: the low-apparent affinity was fixed at 61 μm with a Hill coefficient of 1.5 (corresponding to the mean values of control cells), and the other parameters were adjusted to fit of the data.