Chemoreflex and metaboreflex control during static hypoxic exercise
1 Department of Physiology, Faculty of Medicine, and 2 Department of Cardiology, Erasme Hospital, Free University of Brussels, Brussels, Belgium Submitted 12 October 2004 ; accepted in final form 7 December 2004 To investigate the effects of muscle metaboreceptor activation during hypoxic static exe...
Gespeichert in:
Veröffentlicht in: | American journal of physiology. Heart and circulatory physiology 2005-04, Vol.288 (4), p.H1724-H1729 |
---|---|
Hauptverfasser: | , , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | 1 Department of Physiology, Faculty of Medicine, and 2 Department of Cardiology, Erasme Hospital, Free University of Brussels, Brussels, Belgium
Submitted 12 October 2004
; accepted in final form 7 December 2004
To investigate the effects of muscle metaboreceptor activation during hypoxic static exercise, we recorded muscle sympathetic nerve activity (MSNA), heart rate, blood pressure, ventilation, and blood lactate in 13 healthy subjects (22 ± 2 yr) during 3 min of three randomized interventions: isocapnic hypoxia (10% O 2 ) (chemoreflex activation), isometric handgrip exercise in normoxia (metaboreflex activation), and isometric handgrip exercise during isocapnic hypoxia (concomitant metaboreflex and chemoreflex activation). Each intervention was followed by a forearm circulatory arrest to allow persistent metaboreflex activation in the absence of exercise and chemoreflex activation. Handgrip increased blood pressure, MSNA, heart rate, ventilation, and lactate (all P < 0.001). Hypoxia without handgrip increased MSNA, heart rate, and ventilation (all P < 0.001), but it did not change blood pressure and lactate. Handgrip enhanced blood pressure, heart rate, MSNA, and ventilation responses to hypoxia (all P < 0.05). During circulatory arrest after handgrip in hypoxia, heart rate returned promptly to baseline values, whereas ventilation decreased but remained elevated ( P < 0.05). In contrast, MSNA, blood pressure, and lactate returned to baseline values during circulatory arrest after hypoxia without exercise but remained markedly increased after handgrip in hypoxia ( P < 0.05). We conclude that metaboreceptors and chemoreceptors exert differential effects on the cardiorespiratory and sympathetic responses during exercise in hypoxia.
handgrip; hypoxia; muscle sympathetic nerve activity; metaboreceptors; chemoreceptors
Address for reprint requests and other correspondence: R. Naeije, Dept. of Physiology, Erasme Univ. Hospital, 808 Lennik Rd., B-1070 Brussels, Belgium (E-mail: rnaeije{at}ulb.ac.be ) |
---|---|
ISSN: | 0363-6135 1522-1539 |
DOI: | 10.1152/ajpheart.01043.2004 |