Journal article
Vascular reactivity and baroreflex function during hyperthermia in conscious rats
American journal of physiology. Regulatory, integrative and comparative physiology, Vol.279(4), pp.R1282-R1289
10/01/2000
DOI: 10.1152/ajpregu.2000.279.4.R1282
PMID: 11003994
Abstract
The hemodynamic responses to vasoconstrictor agents are blunted during heating in anesthetized rats. It is unknown whether reflex neural responses to these agents are also altered during hyperthermia. Therefore, the purpose of this study was to determine the effect of hyperthermia on the hemodynamic and baroreflex-mediated sympathetic neural responses to vasoactive agents in conscious, unrestrained rats. The splanchnic sympathetic nerve activity (SpNA) and systemic and regional hemodynamic responses to injections of phenylephrine and sodium nitroprusside were measured during normothermia (37°C) and hyperthermia (41.5°C). The hemodynamic responses to phenylephrine and sodium nitroprusside were blunted with heating, whereas the SpNA responses to both agents were augmented or unchanged. At 41.5°C, the baroreflex curves relating heart rate (HR) and SpNA to mean arterial blood pressure were shifted to the right. The operating range and gain of the blood pressure (BP)-HR reflex were significantly reduced during heating, whereas the operating range of the BP-SpNA reflex was augmented at 41.5°C. These results indicate that heating alters the cardiovascular and sympathetic neural responses to vasoactive agents in vivo. Furthermore, the data suggest that heating differentially affects arterial baroreflex control of HR and SpNA, shifting both curves toward higher BP values but selectively attenuating baroreflex control of HR.
Details
- Title: Subtitle
- Vascular reactivity and baroreflex function during hyperthermia in conscious rats
- Creators
- Michael P Massett - Departments of Exercise Science andStephen J Lewis - Pharmacology, The University of Iowa, Iowa City, Iowa 52242; andHarald M Stauss - Departments of Exercise Science and, Humboldt Universität Berlin, Physiologisches Institut, 10117 Berlin, GermanyKevin C Kregel - Departments of Exercise Science and
- Resource Type
- Journal article
- Publication Details
- American journal of physiology. Regulatory, integrative and comparative physiology, Vol.279(4), pp.R1282-R1289
- DOI
- 10.1152/ajpregu.2000.279.4.R1282
- PMID
- 11003994
- ISSN
- 0363-6119
- eISSN
- 1522-1490
- Language
- English
- Date published
- 10/01/2000
- Academic Unit
- Radiation Oncology; Provost Office Administration; Health and Human Physiology
- Record Identifier
- 9984213308602771
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