Pre-existing inflammatory state compromises heat tolerance in rats exposed to heat stress

Lim, Chin Leong and Wilson, Gary and Brown, Lindsay and Coombes, Jeff S. and Mackinnon, Laurel T. (2007) Pre-existing inflammatory state compromises heat tolerance in rats exposed to heat stress. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 292 (1). R186-R194. ISSN 0363-6119

Abstract

This study investigated the roles of endotoxemia and heat-induced tissue damage in the pathology of heat stroke. In groups of eight, male Wistar rats were treated with heat exposure only (HE), or heat exposure with turpentine (T+HE), dexamethasone (D+HE), and turpentine and dexamethasone combined (TD+HE). The rats remained sedated for 2h after receiving the respective treatments, followed by heat exposure until the core temperature (Tc) was 42°C for 15min; control rats received turpentine (T), dexamethasone (D), and turpentine and dexamethasone (TD) without heat stress. Blood samples were collected before treatment (baseline I), after 2 h of passive rest (baseline II), at Tc 40°C (T40), and 15 min after achieving Tc 42°C (T42). No rats died in the nonheat-stressed groups. Survival rate was lowest in the TD+HE rats (37.5%), followed by the HE (62.5%), T+HE (75%), and D+HE (100%) rats (P < 0.05). The duration of survival at T42°C was shortest in the TD+HE rats (9.9 ± 6.2 min) (P < 0.01), followed by the T+HE (11.3 ± 6.1 min) and the HE (12.2 ± 4 min) (P < 0.05) rats. The increase in plasma IL-6 concentrations was highest in the T+HE (352%) and HE (178%) rats (P < 0.05). D+HE treatment suppressed the increases in plasma aspartate transaminase, alanine aminotransferase, and IL-6 and LPS concentrations during severe heat stress. Heat stroke can be triggered by endotoxemia or heat-induced tissue damage, and preexisting inflammation compromises heat tolerance, whereas blocking endotoxemia increases heat tolerance.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: First published 21 Sep 2006 Permanent restricted access to paper due to publisher copyright restrictions.
Depositing User: epEditor USQ
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 09 Sep 2011 07:07
Last Modified: 03 Jul 2013 00:43
Uncontrolled Keywords: dexamethasone; inflammation; turpentine
Fields of Research (FOR2008): 11 Medical and Health Sciences > 1116 Medical Physiology > 111601 Cell Physiology
11 Medical and Health Sciences > 1102 Cardiovascular Medicine and Haematology > 110202 Haematology
10 Technology > 1004 Medical Biotechnology > 100499 Medical Biotechnology not elsewhere classified
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970111 Expanding Knowledge in the Medical and Health Sciences
Identification Number or DOI: doi: 10.1152/ajpregu.00921.2005
URI: http://eprints.usq.edu.au/id/eprint/19368

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