Abstract
Previous observations have indicated that the smooth muscle responsible for rhythmic contraction of intestinal villi is susceptible to autonomic nervous stimulation. In studying the adrenergic receptors of this system, we have found that norepinephrine or phenylephrine (alpha adrenergic receptor agonists) on topical application to the exteriorized jejunal mucosal surface of anesthetized dogs stopped villous activity, whereas isoproterenol (a beta receptor agonist) enhanced it. Phentolamine (alpha adrenergic receptor blockers) antagonized the effect of norepinephrine; propranolol or dichloroisoproterenol (beta receptor blockers) antagonized the effect of isoproterenol. l-Epinephrine (an alpha and beta adrenergic receptor agonist), depending on the dose, slightly stimulated or depressed villous motility. After pretreatment with phentolamine, epinephrine stimulated villous activity. After propranolol, epinephrine exhibited the opposite effect. Combined pretreatment with phentolamine and propranolol prevented all the effects of epinephrine. These results indicate that in intestinal villi alpha receptor stimulation inhibits, whereas beta receptor stimulation enhances villous motility.
Footnotes
- Received January 19, 1970.
- Accepted September 16, 1971.
- © 1972, by The Williams & Wilkins Company
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