Table 1.
Influence of the number of pulses (train length) on the tonic effect of adenosine on electrically evoked [3H]ACh release from myenteric motoneurons of the rat ileum
| Number of pulses | Control | Drugs in S2 (% of control) | |||
|---|---|---|---|---|---|
| S1 (103 dpm g−1) | S2/S1 | ADA (0.5 U ml−1) | Con A (0.1 mg ml−1) | AOPCP (200 μM) | |
| 200 pulses | 44±5 (15) | 0.83±0.11 (4) | −31±6% (7)* | +4±8% (4) | −1±9% (4) |
| 750 pulses | 94±11 (18) | 0.84±0.07 (4) | −32±9% (4)* | −13±4% (4) | +2±9% (5) |
| 1350 pulses | 220±14 (8) | 0.85±0.05 (4) | −38±3% (4)* | −41±4% (4)* | −36±5% (3)* |
Evoked [3H]ACh release was elicited by two trains (S1 and S2) of electrical field stimulation consisting of 200, 750 or 1350 pulses delivered at a 5 Hz frequency (1 ms pulse duration). Values for S1 and S2/S1 are means±s.e.m. ADA (0.5 U ml−1), Con A (0.1 mg ml−1) and AOPCP (200 μM) were applied 15 min before S2. The effects of the drugs on the stimulation (S2)-evoked release of ACh were measured and are expressed as percentage changes (± s.e.m.) in S2/S1 ratios as compared to controls. The number of experiments is between parentheses.
P<0.05 (one-way ANOVA followed by Dunnett's modified t-test), significant differences from the control.