AJP - Gastrointestinal and Liver Physiology, Vol 252, Issue 3 365-G373, Copyright © 1987 by American Physiological Society
Tachykinins: local gastric effects and brain stem responses
W. D. Barber, G. D. Stevenson and T. F. Burks
The gastric motor or mechanical effects of a group of peptides, the
tachykinins, were evaluated in anesthetized cats to determine the
relationship between local motor events and brain stem neurons that
regulate gastric activity. The peptides evaluated were substance P,
physalaemin, and eledoisin. The tachykinin-induced gastric changes were
dose related and were characterized by initial distention-sustained
contraction-late distention phases. At lower doses distention was the
dominant effect with a sustained contraction-late distention response
appearing as the dose increased. The sustained contraction-late distention
phases were frequently accompanied by phasic contractions with a frequency
of 2-4/min. Atropine had a significant effect on the sustained contraction
phase but no effect on the phasic contractions or distention phases.
Bilateral cervical vagotomy had a significant effect on the early
distention phase, suggesting a link with brain stem mechanisms. The
activity of brain stem units that responded to phasic distention of the
stomach reflected the tachykinin-induced changes in gastric distention.
Although the gastric effects of these tachykinins shared distinct
similarities, certain differences in the time sequence of the
distention-contraction interactions suggests the possibility that
dissimilar receptor types may be involved in the mechanisms of action.
Their mechanisms of action may also involve a direct effect on the effector
organ.
