Neuromuscular pharmacology of the anterior intestine of Chaetopterus variopedatus, a filter-feeding polychaete
M Anctil, M Laberge, N Martin (1984) Neuromuscular pharmacology of the anterior intestine of Chaetopterus variopedatus, a filter-feeding polychaete Comp Biochem Physiol C Comp Pharmacol Toxicol 79(2) 343-51Abstract
The motricity of the anterior intestine of Chaetopterus variopedatus was investigated using extracellular electrodes, force displacement transduction and a pharmacological approach. Rhythmic bursts of impulses were associated with peristaltic waves; the latter were not abolished by removal of the ventral nerve cord which caused a drop in tonus. Acetylcholine induced a contracture and an increase in the frequency of peristaltic waves; these effects were potentiated by eserine and reduced by atropine. Similar responses to adrenaline and noradrenaline were antagonized by propranolol and phentolamine in partially different manners. Gamma-aminobutyric acid (GABA) induced large, picrotoxin-sensitive contractures but failed to change the rate of peristalsis. Serotonin (5-HT) produced a short-term increase in the rate of peristalsis as well as a slight contracture, and a long-term inhibition of peristalsis, all actions antagonized by methysergide. The response to GABA was reduced or abolished during the inhibitory phase of the 5-HT effect. A tetrapeptide related to cholecystokinin/gastrin induced contractures and accelerated peristalsis at a concentration as low as 2.5 X 10(-13) M. It is concluded that multiple neurotransmitter pathways may modulate gut motricity by acting on the peristalsis pacemaker as well as on neuromuscular transmission mechanisms.
Links
http://www.ncbi.nlm.nih.gov/pubmed/6151465http://dx.doi.org/10.1016/0742-8413(84)90212-3
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