EFFECTS OF DRUGS AND ELECTRICAL-FIELD STIMULATION ON THE HUMAN LOWER ESOPHAGEAL SPHINCTER

  • 1 January 1979
    • journal article
    • research article
    • Vol. 240  (1) , 169-176
Abstract
Acetylcholine, bethanechol, pentagastrin and dopamine contracted muscle strips cut transversely from the human lower esophageal sphincter (LES). In the presence of hyoscine the contraction to acetylcholine was changed to a relaxation; tolerance was observed to the effect of pentagastrin. Metoclopramide and ATP were only partially effective on LES muscle; some strips were unresponsive, others gave small contractions. Noradrenaline [norepinephrine (NE)], dimethylphenylpiperazinium and histamine relaxed LES muscle. Relaxations to NE were blocked by propranolol. The response of LES muscle to electrical field stimulation [EFS] was dependent on the exact origin of the muscle strip. Muscle cut adjacent to the esophagogastric junction only relaxed, strips cut progressively more rostral to this point showed a biphasic response with the after-contraction becoming more obvious as the distance from the esophagogastric junction increased. Relaxation of LES muscle to EFS appeared to involve non-adrenergic non-cholinergic nerves. Muscle obtained from the terminal esophagus may be identified as the LES if it responds to EFS with only a relaxation.

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