Table 3.
Chronic Effect of Ouabain and Pentamidine on Human Ether-à-go-go Related Gene Activity as Determined in Chronic Tl+ Flux Assays
| Time (min) | Maximum Inhibition (%) | pEC50 | Hill Slope |
|---|---|---|---|
| Ouabain | |||
| 15 |
29.3 ± 2.1 |
5.94 ± 0.16 |
1 |
| 30 |
35.8 ± 2.2 |
5.97 ± 0.09 |
1.87 ± 0.81 |
| 45 |
55.9 ± 1.6 |
6.22 ± 0.05 |
1.46 ± 0.20 |
| 60 |
70.7 ± 1.3 |
6.28 ± 0.04 |
1.28 ± 0.11 |
| 75 |
88.4 ± 1.9 |
6.34 ± 0.04 |
1.19 ± 0.12 |
| 90 |
99.2 ± 1.9 |
6.45 ± 0.04 |
1.64 ± 0.20 |
| 120 |
∼100.0 |
6.80 ± 0.02 |
4.16 ± 0.43 |
| 180 |
∼100.0 |
6.94 ± 0.03 |
4.66 ± 2.10 |
| 240 |
∼100.0 |
7.30 ± 0.02 |
3.43 ± 0.27 |
| 960 (16 h) |
∼100.0 |
7.76 ± 0.02 |
5.72 ± 0.48 |
| Pentamidine | |||
| 240 |
78.7 ± 10.3 |
4.33 ± 0.13 |
1 |
| 480 |
∼100.0 |
4.53 ± 0.08 |
1 |
| 960 | ∼100.0 | 4.95 ± 0.04 | 1.26 ± 0.06 |
Results represent best-fit values ± SE. Cells were first incubated with ouabain or pentamidine for desired time (minutes to hours) at 37°C in cell incubator, washed once with assay buffer, and loaded with Tl+ flux dye solution for 90 min at room temperature in the dark, remaining total human Ether-à-go-go related gene activity was then determined. Initial slope of the curves was normalized to percentages with buffer control as 0% inhibition and complete inhibition (initial slope of around 2 with 10 μM cisapride) as 100% and pooled for analysis in the Prism with built-in four-parameter logistic function. Figures were presented in Figure 3. Potency, Hill slope, and maximum inhibition were reported directly from Prism. While curve-fitting, bottom was constrained to 0%, top was constrained to < 100%, and Hill slope was determine by the built-in comparison function in the Prism. Intracellular (if they entered cells) and residual drugs might be still working after removal of drug solution and during 90 min incubation with Tl+ flux dye.