Interactive effects of hypoxia and hypercapnia on sympathetic nerve activity in humans

M. L. Smith, Seth Hardy, M. E. Dibner-Dunlap

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The combined effects of hypoxia and hypercapnia on the sympathetic nervous system were investigated in nine healthy subjects. Each subject was exposed to 16 gas mixtures in random order; a4X4 matrix of hypoxic (21, 16, 12, 8%) and hypercapnic (0, 2, 4, 6%) gases. Methods: Sympathetic nerve activity (SNA), O 2 saturation, arterial pressure, end tidal CO 2 , and tidal volume were measured continuously before and while breathing each gas mixture for 90 sec. Changes in SNA from the preceding baseline period were determined for each gas mixture. SNA also was segmented into low lung volume phases and high lung volume phases to investigate the modulation of SNA by respiratory phase. Results: Significant main effects differences were found for hypoxia (p<0.01) and hypercapnia (p<0.001), and a trend toward an interaction was apparent. The figure illustrates the individual and interactive effects of CO 2 and O 2 on the SNA response. These effects were accentuated during low lung volume phases of respiration (p<0.05). Conclusions: These data support the hypothesis that combined hypoxia and hypercapnia produce a mutual facilitation effect on SNA which is exaggerated by withdrawal of inhibitory effects of lung inflation. Supported by NtH, HL49266.

Original languageEnglish (US)
JournalFASEB Journal
Volume10
Issue number3
StatePublished - Dec 1 1996

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Hypercapnia
Human Activities
Gas mixtures
Gases
Carbon Monoxide
Lung
Respiration
Neurology
Sympathetic Nervous System
Tidal Volume
Economic Inflation
Modulation
Healthy Volunteers
Arterial Pressure
Hypoxia

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

Cite this

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Interactive effects of hypoxia and hypercapnia on sympathetic nerve activity in humans. / Smith, M. L.; Hardy, Seth; Dibner-Dunlap, M. E.

In: FASEB Journal, Vol. 10, No. 3, 01.12.1996.

Research output: Contribution to journalArticle

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