Document Detail

Effects of hypoxia on respiratory neural output and lower esophageal sphincter pressure in piglets.
MedLine Citation:
PMID:  12084847     Owner:  NLM     Status:  MEDLINE    
We have previously documented anatomic and functional relationships between ventilatory and autonomic neural output. Therefore, we hypothesized in this study that hypoxia-induced changes in respiratory neural output are associated with changes in autonomic regulation of lower esophageal sphincter (LES) pressure. Respiratory neural output, heart rate, and LES pressure were measured before and during a 3-min exposure to 8% oxygen (balance nitrogen) in 12 3- to 7-d-old piglets. Respiratory neural output was determined from diaphragmatic electromyogram and LES pressure from an esophageal catheter. Studies were repeated after atropine administration in eight animals. Hypoxic exposure resulted in significant increases in diaphragmatic amplitude, respiratory rate, and minute diaphragmatic activity as well as heart rate. The biphasic response of diaphragm amplitude peaked at 1 min, whereas the responses of respiratory frequency and heart rate were sustained. Hypoxia caused a 50% increase in LES pressure (p < 0.05), which was eliminated by i.v. atropine administration. Development of apnea during subsequent hyperoxic exposure was always followed by a decline in LES pressure. Hypoxia-induced increase in respiratory neural output and accompanying increase in heart rate are associated with enhanced constrictive output to the LES. Blockade by atropine implicates a peripheral cholinergic mechanism for this LES response. We speculate that whereas hypoxia in the presence of enhanced respiratory neural output seems to be protective against reflux, decreased respiratory drive and accompanying apnea may be associated with a decline in LES tone and predispose to gastroesophageal reflux.
Pakaphan Kiatchoosakun; Ismail A Dreshaj; Jalal M Abu-Shaweesh; Musa A Haxhiu; Richard J Martin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Pediatric research     Volume:  52     ISSN:  0031-3998     ISO Abbreviation:  Pediatr. Res.     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2002-06-26     Completed Date:  2002-12-10     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0100714     Medline TA:  Pediatr Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  50-5     Citation Subset:  IM    
Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Thailand.
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MeSH Terms
Anoxia / physiopathology*
Apnea / physiopathology
Diaphragm / physiology
Esophagogastric Junction / innervation*,  physiology*
Heart Rate
Lung / innervation*
Oxygen / pharmacology
Respiratory Mechanics
Vagus Nerve / physiology
Grant Support
Reg. No./Substance:

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