Effects of heat stress on baroreflex function in humans

Craig G. Crandall, Jian Cui, Thad E. Wilson

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Introduction: Heat stress significantly reduces orthostatic tolerance in humans. The mechanism(s) causing this response remain unknown. The purpose of this review article is to present data pertaining to the hypothesis that reduced orthostatic tolerance in heat stressed individuals is a result of heat stress induced alterations in baroflex function. Methods: In both normothermic and heat stressed conditions baroreflex responsiveness was assessed via pharmacological and non-pharmacological methods. In addition, the effects of heat stress on post-synaptic vasoconstrictor responsiveness were assessed. Results: Generally, whole body heating did not alter baroreflex sensitivity defined as the gain of the linear portion of the baroreflex curve around the operating point. However, whole body heating shifted the baroreflex curve to the prevailing (i.e. elevated) heart rate and muscle sympathetic nerve activity. Finally, the heat stress impaired vasoconstrictor responses to exogenous administration of adrenergic agonists. Conclusion: Current data do not support the hypothesis that reduced orthostatic tolerance associated with heat stress in humans is due to impaired baroreflex responsiveness. This phenomenon may be partially due to the effects of heat stress on reducing vasoconstrictor responsiveness.

Original languageEnglish (US)
Pages (from-to)321-328
Number of pages8
JournalActa Physiologica Scandinavica
Volume177
Issue number3
DOIs
StatePublished - Mar 1 2003

Keywords

  • Blood pressure control
  • Hyperthermia
  • Orthostatic intolerance
  • Skin blood flow

ASJC Scopus subject areas

  • Physiology

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