title: Power spectrum analysis of cardiovascular variability during passive heating in conscious rats.
abstract: The cardiovascular system plays a direct role in the maintenance of body temperature. Whether passive heating alters cardiovascular autonomic modulation in conscious rats is still unknown. This study investigated the effects of passive heating on systolic blood pressure variability (SBPV) and heart rate variability (HRV) in conscious rats and the involvement of the renin-angiotensin system in the passive heating effects on SBPV and HRV. Fourteen male Wistar rats were randomly assigned to the control group or the losartan treatment group. A catheter was implanted in the left carotid artery to record pulsatile arterial pressure (PAP), and a telemetry sensor was implanted in the abdominal cavity to measure body temperature (Tbody). After recovering from surgery, the animals were subjected to a passive heating protocol (35°C; 30min) in resting conditions, during which Tbody, tail skin temperature and PAP were measured. The mean arterial pressure, systolic and diastolic blood pressure, heart rate, double product (i.e., the product of systolic blood pressure by heart rate), SBPV and HRV were calculated from the PAP. SBPV and HRV were analyzed in terms of both time and frequency domains. Increases in the thermoregulatory and cardiovascular parameters were observed during passive heating in both groups, and those increases were reflected in the higher time and frequency domains of the SBPV. However, passive heating was not effective in altering HRV. Passive heating altered SBPV but not HRV in conscious rats when they were treated with losartan.
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil.
authors.forename: Anselmo Gomes
authors.initials: AG
authors.lastname: Moura
authors.affiliation: Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Washington
authors.initials: W
authors.lastname: Pires
authors.affiliation: Departamento de Fisiologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Laura Hora Rios
authors.initials: LH
authors.lastname: Leite
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil.
authors.forename: Daise Nunes Queiroz
authors.initials: DN
authors.lastname: da Cunha
authors.affiliation: Escola de Educação Física e Esportes, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Tiago
authors.initials: T
authors.lastname: Peçanha
authors.affiliation: Escola de Educação Física e Esportes, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Jorge Roberto Peurrot
authors.initials: JR
authors.lastname: de Lima
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil.
authors.forename: Antônio José
authors.initials: AJ
authors.lastname: Natali
authors.affiliation: Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil. Electronic address: thales.gomes@ufv.br.
authors.forename: Thales Nicolau
authors.initials: TN
authors.lastname: Prímola-Gomes
mesh_terms: D000818:Animals; D062186:Arterial Pressure; D001341:Autonomic Nervous System / Q000502:physiology; D001794:Blood Pressure; D001831:Body Temperature; D001833:Body Temperature Regulation; D006339:Heart Rate; D006358:Hot Temperature; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012084:Renin-Angiotensin System; D012815:Signal Processing, Computer-Assisted; D013817:Thermography / Q000379:methods
keywords: Cardiovascular autonomic modulation; Heat stress; Thermoregulation