Effects of autonomic drugs on epididymal contractions.

The spontaneous contractility of rat epididymis was recorded in vivo and the effects of various autonomic drugs were studied. Norepinephrine, epinephrine, and orciprenaline produced a sudden increase in tonus and in the size and frequency of epididymal contractions. Phentolamine (an alpha-blocker agent) inhibited the effects of norepinephrine. On the other hand, alprenolol (a beta-blocker agent) inhibited the effects of orciprenaline but did not block the effects of norepinephrine. In addition, phentolamine and alprenolol decreased the spontaneous activity of the epididymis. Acetylcholine produced effects similar to those of norepinephrine. These effects were blocked by atropine. The results described would indicate the presence of the two receptors, alpha and beta, and that both are mediators of stimulatory effects.