Linked Life Data

3654421

Source:http://linkedlifedata.com/resource/pubmed/id/3654421

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1987-11-9
pubmed:abstractText
The electromyogram (EMG) of the diaphragm, lateral rectus, and nuchal and hindlimb muscles were studied during spontaneous activity and during hypercapnia or hypoxemia in eight fetal sheep from 0.5 to 0.8 gestation (73-128 days). At the earliest gestational age, diaphragmatic EMG activity was mainly tonic and associated with tonic activity of somatic muscles. The stimulus for the diaphragmatic activity originated centrally. Brief periods of a rapid-eye-movement (REM) state characterized by phasic lateral rectus and diaphragmatic activity and absence of nuchal activity were recognized. Furthermore, from 0.5 to 0.7 gestation onward, activity of all muscles increased. Thereafter increased specificity of activity in relation to the apparent REM and non-rapid-eye-movement (NREM) state occurred. With maturation, phasic diaphragmatic activity increased at the expense of tonic activity. The most striking effect of maturation on apnea was a greater proportion of apnea lasting greater than 1 min, but the total duration of apnea as a percent of a total recording remained unchanged. The quantitative response to hypercapnia during maturation was independent of the pattern of spontaneous diaphragmatic activity. Hypercapnia at 0.5 gestation changed the pattern of diaphragmatic EMG activity from mainly tonic to phasic. Thus the central chemoreceptors and appropriate neuronal pathways are present and functional as early as 0.5 gestation. Hypercapnia at 0.5 gestation caused a shift in diaphragmatic EMG power to lower frequencies similar to that found during control conditions in the older fetus. This might suggest that during maturation there is increased recruitment of phrenic motoneurons. Hypoxemia abolished tonic somatic activity at 0.5 gestation and decreased phasic diaphragmatic activity at more advanced gestational ages. Therefore the central inhibitory mechanisms of hypoxemia are developed by 0.5 gestation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
8750-7587
pubmed:author
pubmed:issnType
Print
pubmed:volume
63
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
609-22
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Maturation of spontaneous fetal diaphragmatic activity and fetal response to hypercapnia and hypoxemia.
pubmed:affiliation
Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't