Journal article
Mechanism for pressor response to nonexertional heating in the conscious rat
Journal of applied physiology (1985), Vol.71(1), pp.192-196
07/01/1991
DOI: 10.1152/jappl.1991.71.1.192
PMID: 1917742
Abstract
The purpose of this study was to determine the systemic hemodynamic mechanism(s) underlying the pressor response to nonexertional heat stress in the unrestrained conscious rat. After a 60-min control period [ambient temperature (Ta) 24 degrees C], male Sprague-Dawley rats (260–340 g) were exposed to a Ta of 42 degrees C until a colonic temperature (Tc) of 41 degrees C was attained. As Tc rose from control levels (38.1 +/- 0.1 degrees C) to 41 degrees C, mean arterial blood pressure (carotid artery catheter, n = 33) increased from 124 +/- 2 to 151 +/- 2 mmHg (P less than 0.05). During this period, heart rate increased (395 +/- 5 to 430 +/- 6 beats/min, P less than 0.05) and stroke volume remained unchanged. As a result, ascending aorta blood flow velocity (Doppler flow probe, n = 8), used as an index of cardiac output, did not change from control levels during heating, but there was a progressive Tc-dependent increase in systemic vascular resistance (+30% at end heating, P less than 0.05). This systemic vasoconstrictor response was associated with decreases in blood flow (-31 +/- 9 and -21 +/- 5%) and increases in vascular resistance (94 +/- 16 and 53 +/- 8%; all P less than 0.05) in the superior mesenteric and renal arteries (n = 8 each) and increases in plasma norepinephrine (303 +/- 37 to 1,237 +/- 262 pg/ml) and epinephrine (148 +/- 28 to 708 +/- 145 pg/ml) concentrations (n = 12, P less than 0.05).
Details
- Title: Subtitle
- Mechanism for pressor response to nonexertional heating in the conscious rat
- Creators
- Kevin C Kregel - Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721J Michael Overton - Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721David G Johnson - Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721Charles M Tipton - Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721Douglas R Seals - Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721
- Resource Type
- Journal article
- Publication Details
- Journal of applied physiology (1985), Vol.71(1), pp.192-196
- DOI
- 10.1152/jappl.1991.71.1.192
- PMID
- 1917742
- ISSN
- 8750-7587
- eISSN
- 1522-1601
- Language
- English
- Date published
- 07/01/1991
- Academic Unit
- Radiation Oncology; Provost Office Administration; Health and Human Physiology
- Record Identifier
- 9984213450502771
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