AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 1 24-G31, Copyright © 1990 by American Physiological Society
Neural control of duodenal motor inhibition by antral contractions in dogs
S. N. Reddy and E. E. Daniel
Department of Biomedical Sciences, McMaster University Medical Centre, Hamilton, Ontario, Canada.
The mechanism of the inhibition of proximal duodenal motor activity by
carbachol-induced antral contractions or by field stimulation was studied
in anesthetized dogs that had strain gauges sutured 5 and 10 cm from the
pylorus on the antrum and duodenum. The duodenum was excited by vagal
stimulation or distal duodenal field stimulation. Duodenal inhibition was
studied 1) during a control period and after the pylorus was transected
followed by administration of phentolamine, 2) during control and after
phentolamine followed by pyloric transection, 3) during control and after
prazosin followed by yohimbine, and 4) during control and after yohimbine.
Duodenal inhibition was greater when the antral stimulation or duodenal
contractions were near the pylorus. Pyloric transection did not
significantly reduce this inhibition; phentolamine then abolished it.
Prazosin did not abolish inhibition but yohimbine did. In conclusion,
antroduodenal inhibition under our experimental conditions was mediated
primarily by sympathetic nerves modulating the activity of duodenal
cholinergic nerves, which possess alpha 2-adrenoceptors, and to a less
extent by intrinsic nerves crossing the pylorus.
