Discrete motor effects of neurohumoral and hormonal stimuli on the canine small intestine
Tansy, M.F.; Martin, J.S.; Landin, W.E.; Kendall, F.M.
Surgery Gynecology and Obstetrics 150(6): 827-838
1980
ISSN/ISBN: 0039-6087 PMID: 6103590 Document Number: 161253
A split bowel preparation for mechanically decoupling the muscle layers of the small intestine was produced in mongrel dogs of both sexes to demonstrate the discrete and joint influences of sympathetic innervation, various enterohormones and hormone-like agents upon the motor activity of the canine small bowel. Electrical centripetal vagal stimulation caused a tonic contraction of the muscularis mucosa in nearly every instance; the magnitude often was of the same order as that obtained after the i.v. administration of epinephrine hydrochloride. The most common effect of centripetal vagal stimulation and administration of epinephrine on the outer musculature was a transient decrease in tonicity. Following the intra-arterial administration of acetylcholine chloride, there was a significant increase in the motility of both the muscularis mucosa and muscularis externa. The responses to bolus doses of histamine dihydrochloride at a similar dose range were qualitatively similar to the responses to the acetylcholine chloride. Bolus intra-arterial doses of serotonin induced similar increases in motor activities of muscularis mucosa and muscularis externa. Gastrin, secretin, cholecystokinin and somatostatin all markedly increased the segmenting activity of the muscularis mucosa. With the possible exception of gastrin, none of these agents increased the contractile activity of the muscularis externa. Vasoactive inhibitor peptide decreased the segmenting activity of the muscularis mucosa and also increased somewhat the spontaneous activity of the muscularis externa. Apparently the muscularis mucosa of the canine small bowel is independently responsive either to reflex stimulation or to a variety of neurohumors and enterohormones and it is a significant effector system in its influence on motor function in the small intestine.