Influence of ventilation and hypocapnia on sympathetic nerve responses to hypoxia in normal humans

Virend Somers, A. L. Mark, D. C. Zavala, F. M. Abboud

Research output: Contribution to journalArticle

277 Citations (Scopus)

Abstract

The sympathetic response to hypoxia depends on the interaction between chemoreceptor stimulation (CRS) and the associated hyperventilation. We studied this interaction by measuring sympathetic nerve activity (SNA) to muscle in 13 normal subjects, while breathing room air, 14% O2, 10% O2, and 10% O2 with added CO2 to maintain isocapnia. Minute ventilation (V̇E) and blood pressure (BP) increased significantly more during isocapnic hypoxia (IHO) than hypocapnic hypoxia (HHO). In contrast, SNA increased more during HHO [40 ± 10% (SE)] than during IHO (25 ± 19%, P < 0.05). To determine the reason for the lesser increase in SNA with IHO, 11 subjects underwent voluntary apnea during HHO and IHO. Apnea potentiated the SNA responses to IHO more than to HHO. SNA responses to IHO were 17 ± 7% during breathing and 173 ± 47% during apnea whereas SNA responses to HHO were 35 ± 8% during breathing and 126 ± 28% during apnea. During ventilation, the sympathoexcitation of IHO (compared with HHO) is suppressed, possibly for two reasons: 1) because of the inhibitory influence of activation of pulmonary afferents as a result of a greater increase in V̇E, and 2) because of the inhibitory influence of baroreceptor activation due to a greater rise in BP. Thus in humans, the ventilatory response to chemoreceptor stimulation predominates and restrains the sympathetic response. The SNA response to chemoreceptor stimulation represents the net effect of the excitatory influence of the chemoreflex and the inhibitory influence of pulmonary afferents and baroreceptor afferents.

Original languageEnglish (US)
Pages (from-to)2095-2100
Number of pages6
JournalJournal of Applied Physiology
Volume67
Issue number5
StatePublished - 1989
Externally publishedYes

Fingerprint

Hypocapnia
Ventilation
Apnea
Respiration
Pressoreceptors
Hypoxia
Blood Pressure
Lung
Hyperventilation

Keywords

  • apnea
  • Sympathetic activity

ASJC Scopus subject areas

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

Cite this

Influence of ventilation and hypocapnia on sympathetic nerve responses to hypoxia in normal humans. / Somers, Virend; Mark, A. L.; Zavala, D. C.; Abboud, F. M.

In: Journal of Applied Physiology, Vol. 67, No. 5, 1989, p. 2095-2100.

Research output: Contribution to journalArticle

Somers, Virend ; Mark, A. L. ; Zavala, D. C. ; Abboud, F. M. / Influence of ventilation and hypocapnia on sympathetic nerve responses to hypoxia in normal humans. In: Journal of Applied Physiology. 1989 ; Vol. 67, No. 5. pp. 2095-2100.
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