Aim: To investigate testicular torsion-induced changes on the electrical field stimulation (EFS)-induced contractions in rabbit vasa deferentia and to evaluate the effect of mexiletine. Methods: 18 male New Zealand albino rabbits were used in this experiment. Rabbits were divided into three groups: (1) control group (n = 6); (2) torsion group (n = 6), and (3) mexiletine group (n = 6). In the control group, vasa deferentia on both sides were harvested. In the torsion and mexiletine groups, the left testes of the rabbits were subjected to 7200 of clockwise torsion for 2 h and then detorsion was performed. In the mexiletine group, 50 mg/kg i.p. mexiletine was administered 1 h before detorsion. Following 24 h of the torsion, vasa deferentia on both sides were harvested and 2-cm strips including both the prostatic and epididymal portions were prepared to record EFS-incluced contractions. Results: Testicular torsion caused a significant inhibition in both phases of EFS-induced biphasic contractions of the ipsi- and contralateral vasa deferentia. Mexiletine treatment did not affect these inhibitory responses. Torsion/detorsion of the spermatic cord did not alter exogenously applied noradrenaline-induced contractions in both vasa deferentia. However, KCl-induced contractions diminished significantly in ipsilateral vas deferens of the torsion group and mexiletine restored this inhibition. Conclusions: Unilateral testicular torsion/detorsion leads to inhibition in both phases of EFS-induced biphasic contractions of the ipsi- and Contralateral vasa deferentia by causing a defect in presynaptic nerve transmission. However, mexiletine has no effect on this inhibition. Inhibition of the KCl-induced contractions in the ipsilateral vas deferens, which indicates postsynaptic tissue damage, is restored by administering mexiletine I h prior to detorsion. Copyright (c) 2006 S. Karger AG, Basel.