Effect of dihydroetorphine on contraction response of guinea pig ileum, mouse, and rabbit vas deferens induced by electric field stimulation in vitro

Dihydroetorphine (DHE) inhibited contraction response of isolated guinea pig ileum and mouse vas deferens induced by electric field stimulation with IC50 values of (4.4 +/- 4.3) x 10(-16) mol.L-1 and (1.1 +/- 1.4) x 10(-18) mol.L-1 respectively. These effects of DHE were antagonized by naloxone (Nal). On guinea pig ileum, the antagonistic effect of Nal against DHE was similar to those against morphine and etorphine. However, on mouse vas deferens, the antagonistic effect of Nal against DHE was more potent than those against morphine and etorphine. Besides, DHE showed antagonistic effect on k-receptors in isolated rabbit vas deferens.