Journal of Applied Physiology Millar Instruments
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J Appl Physiol 95: 272-278, 2003. First published March 7, 2003; doi:10.1152/japplphysiol.00057.2003
8750-7587/03 $5.00
This Article
Right arrow Full Text Free
Right arrow Full Text (PDF) Free
Right arrow All Versions of this Article:
95/1/272    most recent
00057.2003v1
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Web of Science (1)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ray, A. D.
Right arrow Articles by Krasney, J. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ray, A. D.
Right arrow Articles by Krasney, J. A.

Exercise delays the hypoxic thermal response in rats

A. D. Ray,1 A. J. Roberts,2 S. D. Lee,1 G. A. Farkas,1 C. Michlin,1 D. I. Rifkin,3 P. T. Ostrow,4 and J. A. Krasney2

Departments of 1Exercise and Nutrition Science, 2Physiology and Biophysics, 3Neurology, and 4Pathology and Anatomical Sciences and The Center for Sleep Disorders Research, Schools of Public Health and Health Professions and Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214

Submitted 21 January 2003 ; accepted in final form 3 March 2003

Exercise exacerbates acute mountain sickness. In infants and small mammals, hypoxia elicits a decrease in body temperature (Tb) [hypoxic thermal response (HTR)], which may protect against hypoxic tissue damage. We postulated that exercise would counteract the HTR and promote hypoxic tissue damage. Tb was measured by telemetry in rats (n = 28) exercising or sedentary in either normoxia or hypoxia (10% O2, 24 h) at 25°C ambient temperature (Ta). After 24 h of normoxia, rats walked at 10 m/min on a treadmill (30 min exercise, 30 min rest) for 6 h followed by 18 h of rest in either hypoxia or normoxia. Exercising normoxic rats increased Tb (°C) vs. baseline (39.68 ± 0.99 vs. 38.90 ± 0.95, mean ± SD, P < 0.05) and vs. sedentary normoxic rats (38.0 ± 0.09, P < 0.05). Sedentary hypoxic rats decreased Tb (36.15 ± 0.97 vs. 38.0 ± 0.36, P < 0.05) whereas Tb was maintained in the exercising hypoxic rats during the initial 6 h of exercise (37.61 ± 0.55 vs. 37.72 ± 1.25, not significant). After exercise, Tb in hypoxic rats reached a nadir similar to that in sedentary hypoxic rats (35.05 ± 1.69 vs. 35.03 ± 1.32, respectively). Tb reached its nadir significantly later in exercising hypoxic vs. sedentary hypoxic rats (10.51 ± 1.61 vs. 5.36 ± 1.83 h, respectively; P = 0.002). Significantly greater histopathological damage and water contents were observed in brain and lungs in the exercising hypoxic vs. sedentary hypoxic and normoxic rats. Thus exercise early in hypoxia delays but does not prevent the HTR. Counteracting the HTR early in hypoxia by exercise exacerbates brain and lung damage and edema in the absence of ischemia.

thermoregulation; hypoxic tissue damage; cerebral edema; pulmonary edema; altitude illness


Address for reprint requests and other correspondence: J. A. Krasney, Dept. of Physiology and Biophysics, 124 Sherman Hall, School of Medicine and Biomedical Sciences, Univ. at Buffalo, Buffalo, NY 14214 (E-mail: krasney{at}Buffalo.edu).






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2003 by the American Physiological Society.