Phenylephrine-induced elevations in arterial blood pressure are attenuated in heat-stressed humans

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

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

To test the hypothesis that phenylephrine-induced elevations in blood pressure are attenuated in heat-stressed humans, blood pressure was elevated via steady-state infusion of three doses of phenylephrine HCl in 10 healthy subjects in both normothermic and heat stress conditions. Whole body heating significantly increased sublingual temperature by ∼0.5°C, muscle sympathetic nerve activity (MSNA), heart rate, and cardiac output and decreased total peripheral vascular resistance (TPR; all P < 0.005) but did not change mean arterial blood pressure (MAP; P > 0.05). At the highest dose of phenylephrine, the increase in MAP and TPR from predrug baselines was significantly attenuated during the heat stress [AMAP 8.4 ± 1.2 mmHg; ATPR 0.96 ± 0.85 peripheral resistance units (PRU)] compared with normothermia (ΔMAP 15.4 ± 1.4 mmHg, ΔTPR 7.13 ± 1.18 PRU; all P< 0.001). The sensitivity of baroreflex control of MSNA and heart rate, expressed as the slope of the relationship between MSNA and diastolic blood pressure, as well as the slope of the relationship between heart rate and systolic blood pressure, respectively, was similar between thermal conditions (each P > 0.05). These data suggest that phenylephrine-induced elevations in MAP are attenuated in heat-stressed humans without affecting baroreflex control of MSNA or heart rate.

Original languageEnglish (US)
Pages (from-to)R1221-R1226
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume283
Issue number5 52-5
DOIs
StatePublished - Nov 1 2002

Keywords

  • Baroreflex sensitivity
  • Heart rate
  • Muscle sympathetic nerve activity
  • Vasoconstrictor agents
  • Whole body heating

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Fingerprint Dive into the research topics of 'Phenylephrine-induced elevations in arterial blood pressure are attenuated in heat-stressed humans'. Together they form a unique fingerprint.

Cite this