Contents lists available at ScienceDirect Journal of Thermal Biology journal homepage: www.elsevier.com/locate/jtherbio Spontaneously hypertensive rats have greater impairments in regulating abdominal temperature than brain cortex temperature following physical exercise Lucas R. Drummond a,b , Ana C. Kunstetter c , Helton O. Campos b , Filipe F. Vaz c , Filipe R. Drummond a , André G.P. Andrade d , Cândido C. Coimbra b , Antônio J. Natali a , Samuel P. Wanner c,* , Thales N. Prímola-Gomes a a Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil b Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil c Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil d Laboratório de Biomecânica, Departamento dos Esportes, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil ARTICLE INFO Keywords: Hypertension Hyperthermia Post-exercise Recovery Thermoregulation Warm environment ABSTRACT This study aimed to evaluate the changes in brain (T brain ) and abdominal (T abd ) temperatures in spontaneously hypertensive rats (SHRs) following fatiguing exercise. Male normotensive Wistar rats (NWRs) and SHRs were used at 16 weeks of age. Their arterial pressure was measured by tail plethysmography prior to the experiments to confirm the hypertensive status of the SHRs. Then, the rats underwent implantation of an abdominal tem- perature sensor to measure T abd and a guide cannula in the frontal cortex to enable the insertion of a thermistor to measure T brain . After a familiarization period, each animal was subjected to incremental speed exercises until fatigue in either a temperate (25 °C) or warm (32 °C) environment, followed by a 60-min post-exercise period at the same temperature at which they exercised. T brain ,T abd and tail-skin temperature (T skin ) were measured every min throughout the experiments. SHRs exhibited higher T abd values than NWRs, and these higher values were transiently and persistently observed at 25 °C and 32 °C, respectively. For example, at 32 °C, T abd was 0.84 °C higher in SHRs at the 25th min (large effect size). In contrast, regardless of the ambient temperature, SHRs exhibited similar T brain values as NWRs, indicating preserved T brain regulation following exercise in hypertensive rats. SHRs presented higher T skin during the last half of the post-exercise period at 25 °C, whereas no inter-group differences were observed at 32 °C. In conclusion, the present results highlight that SHRs, an animal model that mimics uncontrolled essential hypertension in humans, exhibited greater impairments in regulating T abd than T brain during the post-exercise period. 1. Introduction The core body temperature of mammals is tightly controlled within narrow limits by a precise, well-coordinated balance between the rates of heat production and heat loss (Wanner et al., 2015; Webb, 1995). This precise control is observed, for example, in freely moving rats, which present small fluctuations in core temperature when exposed to a wide range of ambient temperatures (Yang and Gordon, 1996). How- ever, some particular conditions cause the rats’ core temperature to deviate from these narrow limits; these conditions include the devel- opment of a systemic inflammatory response (Wanner et al., 2017) and performance of a physical exercise session (Wanner et al., 2015). The increase in core temperature observed during the early mo- ments of physical exercise results from a temporary imbalance between the above-mentioned rates, with the rate of heat production increasing faster than the rate of cutaneous heat loss (Gleeson, 1998; Webb, 1995). As physical exercise continues, heat loss mechanisms are then acti- vated, and a steady-state core temperature is observed when exertion is https://doi.org/10.1016/j.jtherbio.2019.04.011 Received 22 January 2019; Received in revised form 16 April 2019; Accepted 18 April 2019 * Corresponding author. Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil. E-mail addresses: lucas.rios.drummond@gmail.com (L.R. Drummond), aninhakunstetter@gmail.com (A.C. Kunstetter), heltoncofisio@hotmail.com (H.O. Campos), filipevaz1988@hotmail.com (F.F. Vaz), filipe.drummond13@gmail.com (F.R. Drummond), andreguto@yahoo.com.br (A.G.P. Andrade), coimbrac@icb.ufmg.br (C.C. Coimbra), anatali@ufv.br (A.J. Natali), samuelwanner@ufmg.br, samuelwanner@eeffto.ufmg.br (S.P. Wanner), thales.gomes@ufv.br (T.N. Prímola-Gomes). Journal of Thermal Biology 83 (2019) 30–36 Available online 19 April 2019 0306-4565/ © 2019 Elsevier Ltd. All rights reserved. T