Table 1.
Effect of substance P (SP) and [βAla8]-neurokinin A (4–10) (NKA) on passive membrane properties and firing parameters in phasic firing neurons.
| Phasic cells | control (n=30) | SP (n=30) | Percent change | Control (n=9) | NKA (n=9) | Percent change |
|---|---|---|---|---|---|---|
| Cm (pF) | 44±2 | 42±3 | ||||
| RP (mV) | −53±1 | −57±1 (P<0,001) | +7 | −55±1 | −58±1 | +7 |
| Rm (MΩ) | 198±14 | 266±15 (P<0.05) | +34 | 176±14 | 268±13 (P<0.001) | +52 |
| AP Threshold (mV) | −23±1 | −34±1 (P<0.001) | +53 | −22±1 | −33±1 (P<0.001) | +48 |
| dV/dtmax (V/s) | 27±1 | 33±2 (P<0.05) | +22 | 25±1 | 30±2 (P<0.05) | +18 |
| OS (mV) | 23±1 | 28±2 (P<0.05) | +20 | 18±2 | 24±2 (P<0.05) | +30 |
| AP50(ms) | 3.7±0.2 | 4.1±0.2 (ns) | +10 | 3.4±0.2 | 3.7±0.3 (ns) | +8 |
| rise time (ms) | 1.2±0.1 | 1.11±0.04 (ns) | −7 | 1.07±0.07 | 1.02±0.04 (ns) | −5 |
| decay time (ms) | 3.0±0.2 | 3.4±0.2 (ns) | +13 | 2.8±0.2 | 3.5±0.3 (ns) | +24 |
| tauAHP (ms) | 36±2 | 90±7 (P<0.001) | 149 | 44±3 | 130±6 (P<0.001) | 194 |
Cm, membrane capacitance; RP, resting potential; Rm, membrane resistance. The action potential (AP) parameters were determined for single spike responses, just above threshold, to current injections 5 ms in duration and of 50 to 200 pA intensities: dV/dtmax, maximum rate of rise; OS, overshoot; AP50, duration of AP at 50% maximum amplitude; tauAHP is the time constant of hyperpolarizing afterpotential decay. Averages; standard error of the mean (SEM); t-test relative to values before application of drugs (control), 2 tailed, unequal variance, level of significance: ns-not significant, p < 0.05, or p < 0.001.