Effects of mexiletine on electrical field stimulation-induced contractile responses in the ipsilateral and contralateral vasa deferentia after unilateral testicular torsion/detorsion.
OBJECTIVE
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 720 degrees 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-induced 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 1 h prior to detorsion.
Ozen
Ibrahim Onur
IO
Department of Pediatric Surgery, Faculty of Medicine, Gazi University, Beşevler Ankara, Turkey. onurozen@gazi.edu.tr
Vural
Ismail Mert
IM
Moralioğlu
Serdar
S
Barun
Sureyya
S
Ercan
Zeynep Sevim
ZS
Sarioğlu
Yusuf
Y
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004558:Electric Stimulation; D008297:Male; D008801:Mexiletine / Q000494:pharmacology* / Q000627:therapeutic use; D009119:Muscle Contraction / Q000187:drug effects*; D011817:Rabbits; D013086:Spermatic Cord Torsion / Q000188:drug therapy*; D014649:Vas Deferens / Q000187:drug effects*
D000889:Anti-Arrhythmia Agents; D008801:Mexiletine