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 mod el of stress, to determine any changes in sympathetic activity as a result of stress in the ipsilateral testis, which decreases blood flow to the cont ralateral testis. Materials and methods The study comprised two groups of six rats each; grou p 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 norad renaline at 37 degrees C and to a solution containing 80 mmol/L K+. Results The vasa deferentia in both groups showed similar contractile respo nses to EFS, which were frequency-dependent and maximal at 80 Hz. Noradrena line-induced contractile activity was lower in amplitude in the vasa defere ntia of group 2 than in the contralateral and ipsilateral vasa deferentia o f group 1, which were not significantly different from each other. All grou ps responded similarly to high K+. Conclusion Intra-abdominal placement of the testes with vas deferens ligati on decreased the contractile response to noradrenaline in the ipsilateral v as deferens without altering the contractile response to EFS and high K+. T his difference could be caused by a reduction in the number of postjunction al alpha-adrenergic receptors or decreased receptor sensitivity. Both possi bilities suggest that the vas deferens may initiate sympathetic activity, w hich may be responsible for contralateral testicular deterioration.