EFFECTS OF STIMULATION OF THE DORSAL MOTOR NUCLEUS OF THE VAGUS ON THE EXTRAHEPATIC BILIARY SYSTEM IN DOGS

This study was performed to determine the distribution of excitatory and inhibitory areas in the dorsal motor nucleus of the vagus (DMV) for the gallbladder and sphincter of Oddi in spinal cord-transected dogs. Microinjection of 0.5 M L-glutamate into the DMV induced various effects on the gallbladder and sphincter of Oddi. Stimulation at the rostral portion of the DMV elicited only excitatory effects on both motilities. Stimulation at the middle portion of the DMV induced excitatory, inhibitory, or combined effects on the gallbladder and excitatory or combined effects on the sphincter of Oddi. Stimulation at the caudal portion of the DMV elicited the three different effects on the sphincter, but only relaxation of the gallbladder. The locations of the excitatory and inhibitory points for the gallbladder and sphincter were mixed in the DMV at the levels near the obex. From these results, it was concluded that the inhibitory points for the gallbladder and sphincter of Oddi are distributed in the caudal portion of the DMV, while their excitatory points are distributed over a wide area and in the more rostral portion of the DMV.