Absence of Selective Brain Cooling in Unrestrained Baboons Exposed to Heat.
From: Physiology, School of Biomedical, Biomolecular and Chemical Science, Univ of Western Australia, Crawley, Australia.
American journal of physiology. Regulatory, integrative and comparative physiology
- Publish Date: May 2007
- ISSN: 0363-6119
- Volume: 292
- Issue: 5
- Pages: R2059-67
- Medium: Print
- Language: English
- Citation (JAMA): Maloney Shane K, Mitchell Duncan, Mitchell Graham, et al. Absence of Selective Brain Cooling in Unrestrained Baboons Exposed to Heat.. Am. J. Physiol. Regul. Integr. Comp. Physiol. May 2007;292:R2059-67
Abstract
To test whether baboons are capable of implementing selective brain cooling, we measured, every 5 min, the temperature in their hypothalamus, carotid arterial bloodstream, and abdominal cavity. The baboons were unrestrained and exposed to 22 degrees C for 7 days and then to a cyclic environment with 15 degrees C at night and 35 degrees C during the day for a further 7 days. During the latter 7 days some of the baboons also were exposed to radiant heat during the day. For three days, during heat exposure, water was withheld. At no time was the hypothalamus cooler than carotid arterial blood, despite brain temperatures above 40 degrees C. With little variation, the hypothalamus was consistently 0.5 degrees C warmer than arterial blood. At high body temperatures, the hypothalamus was sometimes cooler than the abdomen. Abdominal temperature was more variable than arterial blood and tended to exceed arterial blood temperature at higher body temperatures. Hypothalamic temperature cooler than a warm abdomen is not evidence for selective brain cooling. In species that can implement selective brain cooling, the brain is most likely to be cooler than carotid arterial blood when an animal is hyperthermic, during heat exposure, and also dehydrated and undisturbed by human presence. When we exposed baboons to high ambient temperatures while they were water deprived and undisturbed, they never implemented selective brain cooling. We conclude that baboons cannot implement selective brain cooling and can find no convincing evidence that any primate species can do so.
Mesh Headings (Keywords): Abdomen, Animals, Body Temperature Regulation, Brain, Carotid Arteries, Female, Heat, Male, Papio
Check for Full Text / PubMed Unique Identifier (PMID): 17218437
This abstract is part of PubMed, a service of the U.S. National Library of Medicine. PubMed includes more than 17 million citations from MEDLINE and other life science journals for biomedical articles. See Copyright and Disclaimers.
Linked medical terms appearing on this page are added by Healia to help readers find more information and are not part of the original PubMed document.
The data herein was last updated on July 8th, 2008 and may not reflect the most current and accurate data available from NLM.