Document Detail

Influence of successive vagal stimulations on contractions in esophageal smooth muscle of opossum.
MedLine Citation:
PMID:  6853705     Owner:  NLM     Status:  MEDLINE    
Studies were performed in anesthetized opossums to investigate the influence of successive vagal stimuli on esophageal contractions. Mechanical activity was recorded manometrically 5 cm above the lower esophageal sphincter. Contractions in the esophagus were evoked by electrical stimuli of 2.5 mA, and 1-ms pulse duration applied to the cervical vagi, at various train durations and frequencies. Paired or multiple stimuli of 1-s train length were also tested at different interstimulus intervals (ISI). Paired stimuli at an ISI of less than or equal to 3 s and at a frequency of less than or equal to 10 Hz showed refractoriness, i.e., the contractions to the first stimulus inhibited the contraction to the second stimulus. A frequency of 50 Hz showed initial inhibition, i.e., the second stimulus inhibited the contraction to the first stimulus. Repetitive stimuli applied at a rate of 8/min (ISI 6.5 s) evoked contractions to each stimulus. At 15/min, every second or third contraction was inhibited. With stimuli applied at 30/min, contractions occurred only in response to the first and/or the last stimulus; depending upon the frequency of vagal stimulation. The intervening stimuli did not evoke any contractions. A long train stimulus produced an initial, a terminal, or both contractions depending on the stimulation value. These studies show that (a) vagal efferent stimulation causes initial inhibition and refractoriness in the esophageal smooth muscle; (b) the degree of initial inhibition increases with increasing frequency of stimulation; (c) the occurrence of contractions only at the onset and the end of a long train stimulus may be due to the influence of initial inhibition and refractoriness.
J S Gidda; R K Goyal
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical investigation     Volume:  71     ISSN:  0021-9738     ISO Abbreviation:  J. Clin. Invest.     Publication Date:  1983 May 
Date Detail:
Created Date:  1983-07-08     Completed Date:  1983-07-08     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7802877     Medline TA:  J Clin Invest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1095-103     Citation Subset:  AIM; IM    
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MeSH Terms
Electric Stimulation
Esophagus / physiology*
Muscle Contraction*
Muscle, Smooth / physiology*
Vagus Nerve / physiology*
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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