Figure 7
Inhibitory effect of tramadol on peristalsis after pre-treatment with adrenoceptor antagonists (Adreno Antagon). The increase in PPT due to the submaximally effective concentrations of 30 μM (-)-tramadol and 30 μM (+)-tramadol was significantly reduced by the combination of prazosin (α1-adrenoceptor antagonist, 1 μM) plus yohimbine (α2-adrenoceptor antagonist, 1 μM), whereas the effect of 10 μM O-desmethyltramadol on PPT was not affected. The bars represent means with SEM, n = 6 segments. *P < 0.05 as compared with vehicle (Tyrode's solution).