Opioids inhibit neuromuscular transmission in circular muscle of human and baboon jejunum

Citations of this article
Mendeley users who have this article in their library.


Intracellular recording techniques were used to study the effects of methionine enkephalin and dynorphin(1-13) on normal circular smooth muscle of human and baboon jejunum. Tetrodotoxin-sensitive inhibitory junction potentials had a mean (±SEM) amplitude of 21 ± 3.3 mV in human jejunum and 24.1 ± 1.3 mV in baboon jejunum. In both species, exogenously added methionine enkephalin and dynorphin (1-13) decreased inhibitory junction potentials amplitude in a dose-dependent manner with methionine enkephalin being more potent. Both opioid peptides acted on receptors located on axons of intrinsic inhibitory nerves. The effects of both methionine enkephalin and dynorphin(1-13) were blocked by ICI-174,864, a selective δ-receptor antagonist. The selective δ agonist, cyclic [d-penicil-lamine2, d-penicillamine5]enkephalin, and the selective μ agonist, Try-Pro-NMePhe-d-Pro-NH2, (each 10 μmol/L) decreased inhibitory junction potential amplitude by 79% ± 6.9% and 61% ± 4.8%, respectively. The selective k agonist, [trans-3,4-dichloro-N-methyl-N-(2-91-pyrolidinyl)-cyclohexyl]-benzene-acetamide methanesulfonate, (10 μmol/L) had no effect. Although direct postsynaptic opioid receptor blockade of the inhibitory neurotransmitter on the smooth muscle cell has not been ruled out, the authors believe these data suggest that δ and μ receptors were present on inhibitory motor nerves innervating the circular muscle and that methionine enkephalin and dynorphin(1-13) decreased release of inhibitory neurotransmitter(s) by acting on δ receptors. © 1991.




Bauer, A. J., Sarr, M. G., & Szurszewski, J. H. (1991). Opioids inhibit neuromuscular transmission in circular muscle of human and baboon jejunum. Gastroenterology, 101(4), 970–976. https://doi.org/10.1016/0016-5085(91)90723-X

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free