Motor activity of the rat duodenum in vivo: evidence for the existence of an atropine-resistant peristalsis.
The motor activity of the proximal duodenum has been investigated by means of a balloon method in urethane-anaesthetized rats. A series of atropine- (1 mg/kg i.v.) or hexamethonium- (20 mg/kg i.v.) sensitive rhythmic contractions can be demonstrated in the rat duodenum which represents a peristaltic reflex mediated by intramural cholinergic neurons. The atropine-sensitive peristaltic reflex is transiently suppressed by intravenous DMPP (0.1 mg/kg) GABA (3 mg/kg) or noradrenaline (10 micrograms/kg). In rats pretreated with guanethidine (20 mg/kg s.c.) plus naloxone (2 mg/kg i.v.) and theophylline (2 mg/kg i.v.) a second type of peristaltic reflex which is atropine-resistant but hexamethonium-sensitive can be demonstrated. These findings indicate that in the rat small intestine a peristaltic activity can be sustained by both atropine-sensitive and atropine-resistant mechanism, which may explain failure of atropine to affect intestinal motility in conscious rats.
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004386:Duodenum / Q000187:drug effects*; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D008722:Methods; D009638:Norepinephrine / Q000494:pharmacology; D010528:Peristalsis / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D006584:Hexamethonium Compounds; D004246:Dimethylphenylpiperazinium Iodide; D005680:gamma-Aminobutyric Acid; D001285:Atropine; D009638:Norepinephrine