The evaluation of sympathetic system-related contractile activity of the rat vas deferens after ligation and intra-abdominal placement of the testis.

OBJECTIVE: To evaluate the contractile response of the vas deferens in a model of stress, to determine any changes in sympathetic activity as a result of stress in the ipsilateral testis, which decreases blood flow to the contralateral testis. MATERIALS AND METHODS: The study comprised two groups of six rats each; group 1 underwent a sham operation, and in group 2 the right testis was placed into the abdominal cavity and the vas deferens ligated. After 30 days, the vasa deferentia were resected bilaterally and their isometric contractions recorded. Electrical-field stimulation (EFS) was applied through a pair of platinum electrodes and concentration-response curves constructed for noradrenaline at 37 degrees C and to a solution containing 80 mmol/L K+. RESULTS: The vasa deferentia in both groups showed similar contractile responses to EFS, which were frequency-dependent and maximal at 80 Hz. Noradrenaline-induced contractile activity was lower in amplitude in the vasa deferentia of group 2 than in the contralateral and ipsilateral vasa deferentia of group 1, which were not significantly different from each other. All groups responded similarly to high K+. CONCLUSION: Intra-abdominal placement of the testes with vas deferens ligation decreased the contractile response to noradrenaline in the ipsilateral vas deferens without altering the contractile response to EFS and high K+. This difference could be caused by a reduction in the number of postjunctional alpha-adrenergic receptors or decreased receptor sensitivity. Both possibilities suggest that the vas deferens may initiate sympathetic activity, which may be responsible for contralateral testicular deterioration.