STIMULATORY ROLE OF THE DORSAL MOTOR NUCLEUS OF THE VAGUS IN GASTROINTESTINAL MOTILITY THROUGH MYOELECTROMECHANICAL COORDINATION IN CATS

This study was undertaken to investigate the effect of stimulation of the dorsal motor nucleus of the vagus (DMV) on myoelectric activity an d motility of the gastric antrum and duodenum in normal and in vagotom ized cats. 37 cats were starved for 24 h and then anesthetized with cu -chloralose (70-80 mg/kg, iv). Electrical stimulation (0.1 mA, 0.2 ms, 50 Hz) of the left DMV was performed through a stereotaxically insert ed electrode in 19 of the cats. The remaining 18 cats were injected in the left DMV with a glutamate solution (1 M, 200 nl) through an inser ted 3-barreled micropipette. The myoelectric activity (slow wave) and the motility of the gastric antrum (2 cm proximal to the pylorus) and duodenum (3 cm distal to the pylorus) were measured using serosal bipo lar electrodes and intraluminal balloons. Both the electrical and the glutamate stimulations of the DMV markedly increased the occurrence of spike potentials on the antral and duodenal myoelectric activity; how ever, the stimulations significantly decreased the frequency of the an tral slow wave. The stimulations also produced increases in the motili ty of the antrum and duodenum which corresponded to the changes in the myoelectric activity. All the changes in the myoelectric activity and the motility were not observed after the ipsilateral vagotomy. Thus, these results strongly suggest that the dorsal motor nucleus of the va gus has a stimulatory influence on antral and duodenal motility throug h myoelectromechanical coordination via the vagus nerve in cats.