Aortic baroreflex control of heart rate after 15 days of simulated microgravity exposure

C. G. Crandall, K. A. Engelke, V. A. Convertino, P. B. Raven

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

To determine the effects of simulated microgravity on aortic baroreflex control of heart rate, we exposed seven male subjects (mean age 38 ± 3 yr) to 15 days of bed rest in the 6° head-down position. The sensitivity of the aortic-cardiac baroreflex was determined during a steady-state phenylephrine- induced increase in mean arterial pressure combined with lower body negative pressure to counteract central venous pressure increases and neck pressure to offset the increased carotid sinus transmural pressure. The aortic-cardiac baroreflex gain was assessed by determining the ratio of the change in heart rate to the change in mean arterial pressure between baseline conditions and aortic baroreceptor-isolated conditions (i.e., phenylephrine + lower body negative pressure + neck pressure stage). Fifteen days of head-down tilt increased the gain of the aortic-cardiac baroreflex (from 0.45 ± 0.07 to 0.84 ± 0.18 beats · min-1 · mmHg-1; P = 0.03). Reductions in blood volume and/or maximal aerobic capacity may represent the underlying mechanism(s) responsible for increased aortic baroreflex responsiveness after exposure to a ground-based analogue of microgravity.

Original languageEnglish (US)
Pages (from-to)2134-2139
Number of pages6
JournalJournal of Applied Physiology
Volume77
Issue number5
StatePublished - 1994

Fingerprint

Weightlessness
Baroreflex
Heart Rate
Lower Body Negative Pressure
Phenylephrine
Pressure
Arterial Pressure
Neck
Head-Down Tilt
Carotid Sinus
Bed Rest
Pressoreceptors
Central Venous Pressure
Blood Volume
Head

Keywords

  • aortic baroreceptors
  • bed rest
  • head-down tilt
  • spaceflight
  • weightlessness

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Aortic baroreflex control of heart rate after 15 days of simulated microgravity exposure. / Crandall, C. G.; Engelke, K. A.; Convertino, V. A.; Raven, P. B.

In: Journal of Applied Physiology, Vol. 77, No. 5, 1994, p. 2134-2139.

Research output: Contribution to journalArticle

Crandall, C. G. ; Engelke, K. A. ; Convertino, V. A. ; Raven, P. B. / Aortic baroreflex control of heart rate after 15 days of simulated microgravity exposure. In: Journal of Applied Physiology. 1994 ; Vol. 77, No. 5. pp. 2134-2139.
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