Contractile Behaviour of Rat Epididymis after Sympathectomy Produced by the Administration of Guanethidine

The effect of guanethidine (a sympatholytic agent) on epididymal contractions was studied in rats, in order to contribute new data on the role of both the adrenergic and cholinergic nerves in the spontaneous motility of the epididymis and also during ejaculation. The first type of activity was increased when adrenergic innervation was damaged, but the amplitude and frequency of contractions reached normal values approximately 3 hours after beginning the records. Since spermatozoa were eliminated after electroejaculation, the second type of contractions was not affected either. As the epididymis and vas deferens were congested with spermatozoa, it is possible to assume that guanethidine caused a functional obstruction in a distal segment of the genital tract. The increase of spontaneous activity could be the response of the epididymal muscle to overcome this obstruction and, therefore, to cause the elimination of spermatozoa into the urethra, which normally occurs in absence of ejaculations. Finally, no pregnancies occurred among female rats mated with treated males, at least up to 150 days after ending treatment.