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Ventilatory responses to muscle metaboreflex activation in chronic obstructive pulmonary disease

Research output: Contribution to journalArticle

Richard M. Bruce, Alice Turner, Michael J. White

Original languageEnglish
JournalJournal of Physiology
Volume594
Issue number20
Early online date14 Jun 2016
DOIs
Accepted/In press5 May 2016
E-pub ahead of print14 Jun 2016
Published15 Oct 2016

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Abstract

Blockade of thin fibre muscle afferent feedback during dynamic exercise reduces exercise hyperpnoea in health and chronic obstructive pulmonary disease (COPD). Therefore, we hypothesised that activation of the muscle metaboreflex at rest would cause hyperpnoea. We evaluated the effect of muscle metaboreflex activation on ventilation, in resting COPD patients and healthy participants. Following a bout of rhythmic hand grip exercise, post exercise circulatory occlusion (PECO) was applied to the resting forearm to sustain activation of the muscle metaboreflex, in 18 COPD patients (FEV1/FVC ratio < 70%), 9 also classified as chronically hypercapnic, and 9 age‐ and gender‐matched controls. The cardiovascular response to exercise and the sustained blood pressure elevation during PECO was similar in patients and controls. During exercise ventilation increased by 6.64 ± 0.84 in controls and significantly (P < 0.05) more, 8.38 ± 0.81 l min−1, in patients. During PECO it fell to baseline levels in controls but remained significantly (P < 0.05) elevated by 2.78 ± 0.51 l min−1 in patients until release of circulatory occlusion, with no significant difference in responses between patient groups. Muscle metaboreflex activation causes increased ventilation in COPD patients but not in healthy participants. Chronic hypercapnia in COPD patients does not exaggerate this response. The muscle metaboreflex appears to be abnormally involved in the control of ventilation in COPD and may be a contributing factor to exercise dyspnoea.

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