There was no difference between DMSO and Tyrode and they were not significantly higher than the baseline (p> 0.05). Arctigenin (ATG) lowered the amplitude in a dose-independent manner. 40 µM ATG was significantly higher than 1µM ATG (p˂ 0.01) [Fig. 3].
However, trachelogenin (TGN) decreased the amplitude in a dose-dependent manner. 20µM TGN had a greater inhibitory effect than 0.5 µM TGN and 1µM ATG (p˂0.05) but comparable to 40 µM ATG (p> 0.999). Furthermore, there was no difference between 1 µM ATG, 10 µM ATG, 1 µM TGN and 10 µM TGN (p> 0.999). [Fig. 3].
10 µM CNQX had no significant inhibition and doubling this concentration did not result in further change in activity (p> 0.05). Adrenoreceptor antagonists propranolol (1 µM) plus phentolamine (1 µM) (Pro+Phe) had no effect (p>0.05) [Fig. 3].
0.5 µM nifedipine had greater activity than 1 µM ATG and 0.5 µM TGN, but comparable to 10 µM ATG and 10 µM TGN (p> 0.05). However, the activity of nifedipine was measured after 5 min, as it abolished spontaneous phasic contractions completely at 0.2 µM and above already afterafter 15 min [Fig. 2]. In contrarycontrast, L NAME had no significant effect (p> 0.05).