Cholecysto-sphincter inhibitory reflex: identification of a reflex and its role in bile flow in a canine model

To study the effect of gallbladder (GB) distension on the sphincter of Oddi (SO), 9 mongrel dogs (mean weight 15.3+/-3.6 kg) were studied. Under anesthesia, the abdomen was opened and the GB and SO were exposed. A balloon-tipped catheter was introduced into the GB and a manometric catheter into the common bile duct so that its fluoroscopically controlled tip lay within the SO. The pressure response of the GB and SO to GB distension by the balloon without and with selective anesthetization of the GB and SO was recorded. The test was repeated in four vagotomized dogs. GB distension effected pressure rise within the GB and pressure drop within the SO. The GB pressure increased progressively as the distending volume increased, while the SO pressure drop was not affected. Selective anesthetization of the GB or the SO produced no SO pressure changes upon GB distension. The SO pressure response to GB distension after vagotomy was similar to that before vagotomy. The SO relaxation on GB contraction, being reproducible and abolished by selective anesthetization of either the SO or the GB, postulates a reflex relationship that we call the cholecysto-sphincter inhibitory reflex. This reflex seems to regulate the bile flow from the GB to the duodenum through the SO.