HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/3/R1298    most recent 00275.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Maloney, S. K. Articles by Blache, D. Search for Related Content PubMed PubMed Citation Articles by Maloney, S. K. Articles by Blache, D.

SLEEP AND TEMPERATURE REGULATION

The contribution of carotid rete variability to brain temperature variability in sheep in a thermoneutral environment

Departments of ¹Physiology: Biomedical and Chemical Science and ³Animal Biology, The University of Western Australia, Crawley, Australia; and ²School of Physiology, University of the Witwatersrand, Parktown, South Africa

Submitted 24 April 2006 ; accepted in final form 24 October 2006

The degree of variability in the temperature difference between the brain and carotid arterial blood is greater than expected from the presumed tight coupling between brain heat production and brain blood flow. In animals with a carotid rete, some of that variability arises in the rete. Using thermometric data loggers in five sheep, we have measured the temperature of arterial blood before it enters the carotid rete and after it has perfused the carotid rete, as well as hypothalamic temperature, every 2 min for between 6 and 12 days. The sheep were conscious, unrestrained, and maintained at an ambient temperature of 20–22°C. On average, carotid arterial blood and brain temperatures were the same, with a decrease in blood temperature of 0.35°C across the rete and then an increase in temperature of the same magnitude between blood leaving the rete and the brain. Rete cooling of arterial blood took place at temperatures below the threshold for selective brain cooling. All of the variability in the temperature difference between carotid artery and brain was attributable statistically to variability in the temperature difference across the rete. The temperature difference between arterial blood leaving the rete and the brain varied from –0.1 to 0.9°C. Some of this variability was related to a thermal inertia of the brain, but the majority we attribute to instability in the relationship between brain blood flow and brain heat production.

brain blood flow; selective brain cooling; sheep; thermoregulation

This article has been cited by other articles:

				A. Fuller, L. C. R. Meyer, D. Mitchell, and S. K. Maloney Dehydration increases the magnitude of selective brain cooling independently of core temperature in sheep Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R438 - R446. [Abstract] [Full Text] [PDF]

				S. K. Maloney, D. Mitchell, G. Mitchell, and A. Fuller Absence of selective brain cooling in unrestrained baboons exposed to heat Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2007; 292(5): R2059 - R2067. [Abstract] [Full Text] [PDF]