Effects of various treatments on parameters calculated from dose–response relationships to 5-HT
| . | EC50 (nM) . | Maximum 5-HT contraction amplitude (normalized to KCl) . | Slope factor p . | N . | Mean R2 . |
|---|---|---|---|---|---|
| Wild-type . | . | . | . | . | . |
| Control | 209 ± 34 | 0.784 ± 0.073 | 1.57 ± 0.25 | 14 | 0.993 ± 0.004 |
| Nifedipine | 355 ± 117 | 0.451 ± 0.065* | 1.46 ± 0.33 | 5 | 0.997 ± 0.003 |
| CaCCInh-A01 | 673 ± 274 | 0.332 ± 0.059** | 1.33 ± 0.25 | 6 | 0.957 ± 0.019 |
| CPA | 309 ± 40 | 0.238 ± 0.045*** | 1.70 ± 0.44 | 4 | 0.996 ± 0.002 |
| Xestospongin C | 70 ± 10 | 0.294 ± 0.068*** | 1.93 ± 0.22 | 6 | 0.989 ± 0.003 |
| 0 Ca2+ | 211 ± 43 | 0.290 ± 0.060*** | 1.46 ± 0.30 | 11 | 0.986 ± 0.005 |
| 0 Ca2+ + CPA | 142 ± 19 | 0.306 ± 0.031*** | 1.12 ± 0.11 | 6 | 0.985 ± 0.011 |
| . | EC50 (nM) . | Maximum 5-HT contraction amplitude (normalized to KCl) . | Slope factor p . | N . | Mean R2 . |
|---|---|---|---|---|---|
| Wild-type . | . | . | . | . | . |
| Control | 209 ± 34 | 0.784 ± 0.073 | 1.57 ± 0.25 | 14 | 0.993 ± 0.004 |
| Nifedipine | 355 ± 117 | 0.451 ± 0.065* | 1.46 ± 0.33 | 5 | 0.997 ± 0.003 |
| CaCCInh-A01 | 673 ± 274 | 0.332 ± 0.059** | 1.33 ± 0.25 | 6 | 0.957 ± 0.019 |
| CPA | 309 ± 40 | 0.238 ± 0.045*** | 1.70 ± 0.44 | 4 | 0.996 ± 0.002 |
| Xestospongin C | 70 ± 10 | 0.294 ± 0.068*** | 1.93 ± 0.22 | 6 | 0.989 ± 0.003 |
| 0 Ca2+ | 211 ± 43 | 0.290 ± 0.060*** | 1.46 ± 0.30 | 11 | 0.986 ± 0.005 |
| 0 Ca2+ + CPA | 142 ± 19 | 0.306 ± 0.031*** | 1.12 ± 0.11 | 6 | 0.985 ± 0.011 |
Individual dose–response curves to 5-HT were least-square fitted to a logistic function of the following formalism: Y = A1 + [(A2 − A1)/(1 + ([5-HT]/EC50)p)], where Y is the contraction amplitude registered in the presence of 5-HT normalized to the high KCl-induced contraction, A1 and A2 are the minimum and maximum contraction amplitudes, respectively, [5-HT] is the concentration of 5-HT, EC50 is the concentration of 5-HT producing a contraction that is 50% of maximum, and p is the slope factor. Because of the biphasic nature of the dose–response curves to 5-HT (see Fig. 1 and text for explanation), only the initial portion of each curve, thus ranging from 0.01 to 1 or 3 μM 5-HT, was analyzed to calculate the parameters shown in the table. All values are means ± SEM pooled from 4 to 14 animals (N). One-way ANOVA tests revealed significant differences in the contraction amplitude between treatments and the control group (bolded numbers) with *P < 0.05, **P < 0.01, and ***P < 0.001. All other comparisons were not significant.