Blockade of the Ferguson reflex by lumbar epidural anaesthesia in the parturient sheep: effects on oxytocin secretion and uterine venous prostaglandin F levels.

The role of oxytocin in the increase in utero-ovarian venous prostaglandin F (PGF) level caused by vaginal distension was investigated by using lumbar epidural anaesthesia to block the oxytocin secretion reflex. Whereas vaginal distension raised jugular venous oxytocin and utero-ovarian venous PGF levels in untreated sheep, neither response occurred after lumbar anaesthesia. Lumbar anaesthesia had no effect on the rise in utero-ovarian venous PGF level caused by administered oxytocin. These findings support the suggestion that a reflex release of oxytocin is involved in the elevation of utero-ovarian venous PGF observed after vaginal distension in parturient sheep.