The rebound excitation triggered by anticholinergic drugs from ovine pyloric antrum, small bowel and gallbladder.
The effect of anticholinergic drugs on gastrointestinal motility is complex and incompletely recognized. Accordingly, in 6 adult sheep bipolar electrodes and strain gage force transducers were surgically attached to the antral, small intestinal and gallbladder wall at the serosal side. During chronic experiments the myoelectric and mechanical recordings were performed in fasted and non-fasted animals before and after various doses of hexamethonium, atropine and pirenzepine given intravenously. Hexamethonium administration triggered rebound excitation after an inhibitory period almost in all the recording sites. Administration of atropine and pirenzepine evoked these secondary contractions mostly in the small intestine and gallbladder. No rebounds were observed when the anticholinergic drugs were given during feeding. In fasted animals, rebound excitation arrived later but more frequently than in non-fasted animals. The excitatory changes were dose-dependent. In the gallbladder, these values were lower than in the small intestine. The frequency of the recurrent pattern was dependent upon the dose of the anticholinergic drug used. It is concluded that nicotinic receptors are more important than muscarinic receptors in the initiation of the rebound excitation in pyloric antrum while in the small bowel and gallbladder the role of both cholinergic receptors is similar. The anticholinergic drugs should be used with caution in all these clinical situations, where the enhancement of gastrointestinal motility must be avoided.
Romański
K W
KW
Department of Animal Physiology, School of Veterinary Medicine, Wrocław Agricultural University, Wrocław, Poland.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004567:Electrodes, Implanted / Q000662:veterinary; D004576:Electromyography; D005215:Fasting; D005704:Gallbladder / Q000187:drug effects / Q000502:physiology*; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D018738:Hexamethonium / Q000494:pharmacology; D007421:Intestine, Small / Q000187:drug effects / Q000502:physiology*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D010890:Pirenzepine / Q000494:pharmacology; D011706:Pyloric Antrum / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology; D011978:Receptors, Nicotinic / Q000502:physiology; D012756:Sheep
D018727:Muscarinic Antagonists; D018722:Nicotinic Agonists; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D018738:Hexamethonium; D010890:Pirenzepine; D001285:Atropine