Increasing uterine response to vaginal distension during late pregnancy in sheep.

Intrauterine pressure changes were monitored in 5 pregnant ewes and uterine venous prostaglandin (PG) F concentrations were determined after distension of the vagina. Uterine contractility and utero-ovarian PGF concentrations were elevated by vaginal distension and the magnitude of both effects increased as parturition approached.