| Ovine fetal laryngeal chemoreflex thresholds and respiratory effects. | |
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MedLine Citation:
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PMID: 9018264 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In newborn infants, laryngeal contact with solutions of low chloride concentration or pH evokes swallowing, laryngeal adduction, and respiratory inhibition (laryngeal chemoreflex). To determine whether the laryngeal chemoreflex is present during fetal life and its effect on fetal respiratory activity, eight time-bred ewes (128 +/- 2 days) were prepared with fetal electrocortical diaphragm and esophageal electrodes and a nasopharyngeal catheter. After a 60-minute control period, increasing volumes (0.1 to 1.0 ml/kg) of 0.15 mol/L NaCl or distilled water (0.05 to 1.0 ml/kg) and decreasing concentrations of NaCl (0.15 to 0.02 mol/L) at a fixed volume (0.3 ml/kg) were sequentially administered through the nasopharyngeal catheter (38 degrees C). The minimum water volume that stimulated swallowing was significantly less than the minimum 0.15 mol/L NaCl volume (0.10 +/- 0.02 vs. 0.70 +/- 0.05 ml/kg). The maximum NaCl concentration that stimulated swallowing was 0.04 +/- 0.01 mol/L During the control period, respiratory activity averaged 14.6 +/- 0.7 breaths/minute and did not change during absent swallow responses or isotonic saline-induced swallows. However, respiratory activity significantly decreased during water (4.7 +/- 0.6 breaths/minute) and hypotonic saline-induced swallow responses (3.7 +/- 0.7 breaths/minute). Fetal electrocortical activity did not change during absent or stimulated swallows. We conclude that laryngeal water or hypotonic saline solution may stimulate fetal swallowing and suppress fetal respiratory activity, similar to the newborn laryngeal chemoreflex. We speculate that an exaggeration of the laryngeal chemoreflex apnea response in the newborn may predispose to sudden infant death syndrome. |
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Authors:
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K Chan; L K Kullama; L Day; A Ogundipe; M G Ross |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Volume: 116 ISSN: 0194-5998 ISO Abbreviation: Otolaryngol Head Neck Surg Publication Date: 1997 Jan |
Date Detail:
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Created Date: 1997-02-26 Completed Date: 1997-02-26 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 8508176 Medline TA: Otolaryngol Head Neck Surg Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 91-6 Citation Subset: IM |
Affiliation:
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Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, Torrance 90502, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Deglutition* Electrodiagnosis Fetus / physiology* Larynx / physiology* Reflex Respiratory Mechanics / physiology* Sheep Sodium Chloride / pharmacology Stimulation, Chemical |
| Grant Support | |
ID/Acronym/Agency:
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DK-43311/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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7647-14-5/Sodium Chloride |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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