EFFECT OF LOCAL INJECTION OF BOTULINUM TOXIN ON SPHINCTER OF ODDI CYCLIC MOTILITY IN DOGS

To study effects of intrasphincteric injections of botulinum toxin on the sphincter of Oddi cyclic motility and responses to motilin and cho lecystokinin, four conscious dogs with duodenal cannula underwent mano metry of the common bile duct, sphincter of Oddi, and duodenum. After baseline recording, each dog had intrasphincteric injections of saline or botulinum toxin. The injections of saline had no effect, whereas b otulinum toxin significantly reduced mean basal pressure, amplitude, a nd motility index of the sphincter of Oddi. These effects took place i n four to seven days and reached a maximum in seven to 10 days. The ba sal pressure returned to the baseline level in 28 weeks, but the ampli tude and motility index remained low. The pressure parameters of motil in-induced premature phase III-like activity also decreased, but actio n of cholecystokinin was not affected. These results indicate that the botulinum toxin injections reduce sphincter of Oddi phasic contractil e activity for a prolonged period of time.