Fluorescence intensity measurements of neurons classified as TH-positive or TH-negative in control and stimulated cultures, in the absence or presence of calcium channel blockers
| Treatment | Fluorescence intensity (mean ± SEM) | |
|---|---|---|
| TH-Negative cells (n = 732) | TH-Positive cells (n = 823) | |
| Control | 5.85 ± 0.40 | 60.38 ± 5.49 |
| 5 Hz | 6.83 ± 0.33 | 45.72 ± 3.94 |
| KCl | 7.89 ± 0.45 | 48.55 ± 3.95 |
| Nimodipine | 9.39 ± 0.46 | 72.40 ± 8.31 |
| 5 Hz + nimodipine | 7.20 ± 0.48 | 46.86 ± 4.33 |
| KCl + nimodipine | 7.22 ± 0.39 | 68.43 ± 8.61 |
| ω-Conotoxin | 10.34 ± 0.45 | 63.89 ± 8.03 |
| 5 Hz + ω-conotoxin | 6.31 ± 0.41 | 49.42 ± 6.17 |
| KCl + ω-conotoxin | 7.33 ± 0.39 | 50.98 ± 4.18 |
E16.5 PG cultures were stimulated at 5 Hz or with 40 mm KCl for 6 hr in the presence or absence of 1 μm ω-conotoxin or 2 μm nimodipine. Fluorescence intensity measurements of single cells were obtained as described in Materials and Methods, and the data are expressed in arbitrary units (mean ± SEM). Between 50 and 135 neurons were analyzed per group. The average fluorescence intensity of cells classified as TH-positive was the same among all treatment groups and was at least sixfold higher than that of cells classified as TH-negative (p ≤ 0.001).