Ventilatory and Cardiovascular Responses to Hypercapnia after 20 Days of Head-Down Bed Rest

Keisho Katayama*, Kohei Sato, Hiroshi Akima, Koji Ishida, Toshio Yanagiya, Hiroaki Kanehisa, Hideoki Fukuoka, Tetsuo Fukunaga, Miharu Miyamura

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Introduction: Few studies have attempted to investigate the influence of prolonged head-down bed rest (HDBR) on hypercapnic ventilatory chemosensitivity, and there are no data available regarding associated changes in arterial BP and heart rate (HR). The aim of this study was to clarify the influence of prolonged HDBR on ventilatory and cardiovascular responses to hypercapnia. Methods: There were five healthy men who participated in this study. Resting ventilatory and cardiovascular responses to hypercapnia were measured by means of Read's CO2 rebreathing method 4 d before and on the 19th day of HDBR. Measured variables included systolic and diastolic BP (SBP and DBP, respectively), inspired minute ventilation (V̇I), and end-tidal partial pressure of CO2 (PETCO2). Results: Ventilatory response to hyperoxic hypercapnia (ΔV̇I/ΔPETCO2) decreased significantly on the 19th day of HDBR (1.42 ± 0.65 to 0.90 ± 0.41 L · min-1 · torr-1, p < 0.05). On the other hand, SBP, DBP, and HR responses (ΔSBP/ΔPETCO2, and ΔHR/ΔPETCO2) were unchanged. Discussion: The results from this study suggest that prolonged HDBR leads to diminished central hypercapnic ventilatory chemosensitivity.

Original languageEnglish
Pages (from-to)312-316
Number of pages5
JournalAviation Space and Environmental Medicine
Issue number4 SEC. I
Publication statusPublished - 2004 Apr
Externally publishedYes


  • Arterial BP
  • Heart rate
  • HR
  • Hypercapnic ventilatory chemosensitivity
  • Hypercapnic ventilatory response

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Pollution
  • Medicine(all)


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