Sex-dependent responses to exertional heat stroke in mice
Abstract
With increasing participation of females in endurance athletics and active military service, it is important to determine if there are inherent sex-dependent susceptibilities to exertional heat injury or heat stroke. In this study we compared responses of male and female adult mice to exertional heat stroke (EHS). All mice were instrumented for telemetry core temperature measurements and were exercise-trained for 3 wk before EHS. During EHS, environmental temperature was 37.5°C (35% RH) while the mice ran on a forced running wheel, using incremental increases in speed. The symptom-limited endpoint was loss of consciousness, occurring at ~42.2°C core temperature. Females ran greater distances (623 vs. 346 m, P < 0.0001), reached faster running speeds (7.2 vs. 5.1 m/min, P < 0.0001), exercised for longer times (177 vs. 124 min, P < 0.0001), and were exposed to greater internal heat loads (240 vs.160°C·min; P < 0.0001). Minimum Tc during hypothermic recovery was ~32.0°C in both sexes. Females lost 9.2% body weight vs. 7.5% in males ( P < 0.001). Females demonstrated higher circulating corticosterone (286 vs 183 ng/ml, P = 0.001, at 3 h), but most plasma cytokines were not different. A component of performance in females could be attributed to greater body surface area/mass and greater external power performance. However, there were significant and independent effects of sex alone and a crossed effect of “sex × power” on performance. These results demonstrate that female mice have greater resistance to EHS during exercise in hyperthermia and that these effects cannot be attributed solely to body size.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 01, 2018
- Source ID
- 10.1152/japplphysiol.00220.2018
Entities
People
- Alex J. Mattingly
- Christian K. Garcia
- Gerard P. Robinson
- Lisa R. Leon
- Michelle A. King
- Orlando Laitano
- Shauna M. Dineen
- Thomas L Clanton
Organizations
- United States Department of Defense
- University of Florida