Swallow-evoked peristalsis in opossum esophagus: role of cholinergic mechanisms.
This study examined the role of cholinergic mechanisms in esophageal smooth muscle of anesthetized opossums. Swallow-induced motility was recorded manometrically before and after treatment with physostigmine or metoclopramide. At the 5-cm site above lower esophageal sphincter (LES) the latency, duration, and amplitude of swallow-evoked contractions were 2.1 +/- 0.12 (SE) s, 1.8 +/- 0.31 s, and 74.5 +/- 6.1 mmHg, respectively. At the 1-cm site the respective values were 4.6 +/- 0.38 s, 3.8 +/- 0.24 s, and 42.0 +/- 4.6 mmHg. The calculated speed of peristalsis was 1.72 +/- 0.21 cm/s. After intravenous treatment with the physostigmine (100 micrograms X kg-1 X h-1), each swallow produced contractions that were simultaneous, repetitive, and of long duration. The values of duration and amplitude of contraction at the 5- and 1-cm site after physostigmine treatment were significantly higher than controls (P less than 0.01). There was a significant decrease in the latency of contraction at all sites. This resulted in a significant faster speed of peristalsis. Atropine (30 micrograms/kg iv) reversed the influence of physostigmine, resulting in a significantly slower speed of peristalsis. Metoclopramide (10 mg/kg iv) resulted in several changes in swallow-evoked contractions similar to those observed after physostigmine treatment. These data suggest that alteration in cholinergic mechanisms results in disordered esophageal peristalsis in the opossum.
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D003679:Deglutition; D004947:Esophagus / Q000187:drug effects / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009893:Opossums; D010528:Peristalsis / Q000187:drug effects*; D010830:Physostigmine / Q000494:pharmacology*
D001285:Atropine; D010830:Physostigmine; D008787:Metoclopramide