Table 3.
Efficacy of bufotenin and tryptamine in comparison with 1 µM of serotonin (5-HT) are evaluated. One micrometer 5-HT is maximally effective to increase force of contraction or beating rate in LA or RA of 5-HT4-TG, respectively. In these experiments, first a concentration response curve to bufotenin/tryptamine was cumulatively established then additionally 5-HT was applied to the isolated atrium. In this way, it was possible to compare the maximum stimulation of 5-HT4-TG receptors. Number of animals ranged from 5 to 7
| Tissue | Parameter | 5-HT (1 µM) | Bufotenin (3 µM) | Tryptamine (100 µM) | Tryptamine (100 µM) + pargyline (50 µM) |
|---|---|---|---|---|---|
| LA | Force (mN) and in % of 1 µM 5-HT | 7.07 ± 0.43, n = 5 | 6.45 ± 0.75, n = 6, 91% ± 5% | 5.74 ± 0.84, n = 5, 81% ± 7% | 4.88 ± 0.71, n = 5, 69% ± 5% |
| LA | TTP (ms) and in % of 1 µM 5-HT | 12.53 ± 0.11, n = 5 | 12.84 ± 0.15, n = 5, 98% ± 0% | 13.28 ± 0.07, n = 5, 94% ± 1% | 13.04 ± 0.04, n = 5, 96% ± 1% |
| LA | TR (ms) and in % of 1 µM 5-HT | 26.77 ± 0.71, n = 5 | 26.08 ± 1.23, n = 5, 103% ± 2% | 27.61 ± 1.25, n = 5, 97% ± 2% | 26.13 ± 1.27, n = 5, 102% ± 2% |
| LA | dF/dtmax (mN/s) and in % of 1 µM 5-HT | 507.42 ± 32.86, n = 5 | 440.7 ± 61.25, n = 5, 87% ± 6% | 393.56 ± 52.26, n = 5, 78% ± 5% | 339.02 ± 43.4, n = 5, 67% ± 4% |
| LA | dF/dtmin (mN/s) and in % of 1 µM 5-HT | − 264.14 ± 16.93, n = 5 | − 233.6 ± 29.54, n = 5, 88% ± 6% | − 217.68 ± 24.09, n = 5, 82% ± 4% | − 186.48 ± 20, n = 5, 71% ± 2% |
| RA | Beating rate (bpm) and in % of 1 µM 5-HT | 369 ± 60, n = 5 | 396 ± 35, n = 7, 107% ± 7% | 388 ± 41, n = 7, 105% ± 5% | 336 ± 62, n = 7, 91% ± 2% |
LA left atrium, RA right atrium, TTP time to peak, TR time of relaxation, dF/dt maximum and minimum of the first derivative of force of contraction