EFFECT OF DISTENSION OF UTERUS AND VAGINA ON UTERINE MOTILITY AND OXYTOCIN RELEASE IN PUERPERAL RABBITS

Abstract

ABSTRACT Uterine responses during distension of either the corpus, cervix or vagina were recorded in conscious, unrestrained rabbits at various times (from 1 h to 8 d) after parturition. The recordings were taken by means of a previously inserted intra-uterine balloon. For comparison, responses to intravenously injected oxytocin and adrenaline were also recorded. There was no indication of a reflex release of oxytocin during these procedures. Distension of either one whole horn with up to 200 ml or one cervix with up to 80 ml of water failed to augment the contractions of the other horn, except in a few cases, when small but uncharacteristic changes in the uterine motility occurred. Vaginal distension produced uterine responses similar to that elicited by adrenaline. Distension of the genital tract is thus considered an inadequate stimulus for reflex release of oxytocin in the rabbit. However, the sensitivity of the method is such that the liberation of smaller amounts than 5 mU cannot be excluded.