Responses of feline esophagus to cervical vagal stimulation.
We used an in vivo feline model to study striated and smooth-muscle esophageal responses to cervical vagal stimulation (VS). Circular esophageal contractions were measured by intraluminal pressure sensors and longitudinal contractions by a force transducer. Responses to VS were recorded before and after giving succinylcholine, atropine, or both. Circular contractions characteristic of striated and smooth muscle were recorded from the mid- and distal esophagus, respectively. With increases in VS frequency, the striated muscle showed rapid, repetitive twitches progressing to tetany. These fast contractions had a square-wave configuration at VS greater than or equal to 10 Hz and were abolished by succinylcholine. In contrast, the slow-twitch circular responses of smooth muscle showed no repetitive twitches and had a bell-shaped configuration. Two types of circular smooth-muscle contractions were observed: 1) A wave "on contractions" occurred 0.5-1.0 s after VS onset, regardless of stimulus length, and 2) infrequent B wave "off contractions" occurred only after stimulus cessation. The longitudinal esophageal contractions had a compound wave form with both striated and smooth-muscle components. Atropine abolished the slow component of the longitudinal contraction, the circular A wave, and peristalsis in the distal esophagus. We conclude that cholinergic motor neurons are an important pathway for eliciting peristalsis in feline esophageal smooth muscle.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002415:Cats; D004558:Electric Stimulation; D004947:Esophagus / Q000294:innervation* / Q000502:physiology; D066298:In Vitro Techniques; D008365:Manometry; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology; D009132:Muscles / Q000502:physiology; D009469:Neuromuscular Junction; D011312:Pressure; D013390:Succinylcholine / Q000494:pharmacology; D014630:Vagus Nerve / Q000502:physiology*
D001285:Atropine; D013390:Succinylcholine