TABLE 1. Effects of low concentrations of nicotine on respiratory pattern and preBötC inspiratory neurons.
| Control | 0.5 μM Nicotine | Percent Control, % | n | P Value | |
|---|---|---|---|---|---|
| XIIn motor activity | |||||
| Respiratory frequency, min−1 | 5.9 ± 1.7* | 16.6 ± 4.0 | 279.7 ± 61.4 | 20 | 5.5 E-10 |
| Inspiratory amplitude (integrated), μV | 135.1 ± 82.3 | 110.3 ± 69.4 | 81.5 ± 12.2 | 20 | 0.00013 |
| Inspiratory duration, ms | 640 ± 185 | 800 ± 300 | 124.0 ± 30.0 | 20 | 0.00077 |
| PreBötC neurons | |||||
| Frequency of sEPSCs, s−1 | 2.68 ± 1.17 | 4.28 ± 1.8 | 176.2 ± 85.4 | 15 | |
| Amplitude of sEPSCs, pA | −19.56 ± 4.98 | −22.24 ± 5.68 | 117.0 ± 30.3 | 15 | |
| Phasic inward current amplitude, pA | −57.7 ± 38.3 | −38.20 ± 26.8 | 65.5 ± 11.7 | 17 | 1.6 E-5 |
| Phasic inward current duration, ms | 934.7 ± 190.5 | 824.1 ± 196.5 | 89.0 ± 15.9 | 17 | 0.013 |
Values are means ± SD; n is sample size. Respiratory frequency is the reciprocal of the average of 6–10 consecutive respiratory periods. The data for nicotine application were measured 3.5–5 min after bath application of nicotine. Inspiratory amplitude, inspiratory duration, phasic inward current amplitude, and phasic inward current duration were measured from the averaged envelope of 5 consecutive inspiratory periods triggered by the up-stroke of the integrated inspiratory bursts from XIIn for each condition. Durations were measured at 20% of peak amplitude. sEPSC indicates spontaneous excitatory postsynaptic current during the expiratory period. The frequency of sEPSCs is the number of sEPSCs divided by total expiration time during ;1 min recording time. Please refer to METHODS and RESULTS for the statistical tests for frequency and amplitude of sEPSCs.
n = 28 for this value.