A qualitative study of factors affecting the contractions of the epididymis and ductus deferens of the ram.

Abstract

Summary. Contractions of the ram ductus deferens-epididymis and epididymis were recorded by cannulating these ducts and measuring the intraluminal pressure changes. The intravenous injection of 0·3 to 10 i.u. oxytocin or 10 to 40 μg adrenaline, or mechanically increasing the pressure within the ducts, stimulated contractions and increased the tonus in the ductus deferens-epididymis. The duration of the response to 2 to 10 i.u. oxytocin was 20 to 70 min. The response to adrenaline and low doses of oxytocin were of a much shorter duration. Vasopressin was 1/15th to 1/20th as potent as oxytocin. The response to oxytocin was not inhibited by adrenaline, α- or β-blocking agents or by atropine. In contrast, an α-receptor-blocking agent (phentolamine) inhibited the response to adrenaline. Copulation initiated contractions of the ductus deferens-epididymis which were similar to the response to intravenous adrenaline. Contractions continued for only a short period after the end of copulation, suggesting that there had been little or no release of oxytocin during copulation.