Linked Life Data

17363686

Source:http://linkedlifedata.com/resource/pubmed/id/17363686

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2007-7-4
pubmed:abstractText
By cooling the hypothalamus during hyperthermia, selective brain cooling reduces the drive on evaporative heat loss effectors, in so doing saving body water. To investigate whether selective brain cooling was increased in dehydrated sheep, we measured brain and carotid arterial blood temperatures at 5-min intervals in nine female Dorper sheep (41 +/- 3 kg, means +/- SD). The animals, housed in a climatic chamber at 23 degrees C, were exposed for nine days to a cyclic protocol with daytime heat (40 degrees C for 6 h). Drinking water was removed on the 3rd day and returned 5 days later. After 4 days of water deprivation, sheep had lost 16 +/- 4% of body mass, and plasma osmolality had increased from 290 +/- 8 to 323 +/- 9 mmol/kg (P < 0.0001). Although carotid blood temperature increased during heat exposure to similar levels during euhydration and dehydration, selective brain cooling was significantly greater in dehydration (0.38 +/- 0.18 degrees C) than in euhydration (-0.05 +/- 0.14 degrees C, P = 0.0008). The threshold temperature for selective brain cooling was not significantly different during euhydration (39.27 degrees C) and dehydration (39.14 degrees C, P = 0.62). However, the mean slope of lines of regression of brain temperature on carotid blood temperature above the threshold was significantly lower in dehydrated animals (0.40 +/- 0.31) than in euhydrated animals (0.87 +/- 0.11, P = 0.003). Return of drinking water at 39 degrees C led to rapid cessation of selective brain cooling, and brain temperature exceeded carotid blood temperature throughout heat exposure on the following day. We conclude that for any given carotid blood temperature, dehydrated sheep exposed to heat exhibit selective brain cooling up to threefold greater than that when euhydrated.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0363-6119
pubmed:author
pubmed:issnType
Print
pubmed:volume
293
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
R438-46
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Dehydration increases the magnitude of selective brain cooling independently of core temperature in sheep.
pubmed:affiliation
School of Physiology, University of the Witwatersrand Medical School, 7 York Road, Parktown 2193, South Africa. fullera@physiology.wits.ac.za
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't