Cardiovascular responses to forearm muscle metaboreflex activation during hypercapnia in humans.
Am J Physiol Regul Integr Comp Physiol
; 309(1): R43-50, 2015 Jul 01.
Article
em En
| MEDLINE
| ID: mdl-25904685
We characterized the cardiovascular responses to forearm muscle metaboreflex activation during hypercapnia. Ten healthy males participated under three experimental conditions: 1) hypercapnia (HCA, PetCO2 : +10 mmHg, by inhalation of a CO2-enriched gas mixture); 2) muscle metaboreflex activation (MMA, by 5 min of local circulatory occlusion after 1 min of 50% maximum voluntary contraction isometric handgrip under normocapnia); and 3) HCA+MMA. We measured mean arterial pressure (MAP), heart rate (HR), and cardiac output (CO); calculated stroke volume (SV), and total peripheral resistance (TPR); and evaluated myocardial oxygen consumption (MVÌo2) and cardiac work (CW) noninvasively. MAP increased in the three experimental conditions but HCA+MMA led to the highest MAP, CO, and HR. Moreover, HCA+MMA increased SV and was associated with the highest MVÌo2 and CW. HCA and MMA exhibited inhibitory interactions with MAP, HR, TPR, MVÌo2, and CW, increases of which were smaller during HCA+MMA than the sum of the increases during HCA and MMA alone (MAP: +28 ± 2 vs. +34 ± 2 mmHg, P < 0.001; HR: +15 ± 2 vs. +22 ± 3 bpm, P < 0.01; TPR: +1.1 ± 1.4 vs. +3.0 ± 1.5 mmHg·l·min(-1), P < 0.05; MVÌo2: +50.25 ± 4.74 vs. +59.48 ± 5.37 mmHg·min(-1)·10(-2), P < 0.01; CW: +59.10 ± 7.52 vs. +63.67 ± 7.71 ml mmHg·min(-1)·10(-4), P < 0.05). Oppositely, HCA and MMA interactions were linearly additive for CO (+2.3 ± 0.4 l/min) and SV (+13 ± 4 ml). We showed that muscle metaboreflex and hypercapnia interact in healthy humans, reducing vasoconstriction but enhancing SV.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Reflexo
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Células Quimiorreceptoras
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Músculo Esquelético
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Metabolismo Energético
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Hemodinâmica
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Hipercapnia
Tipo de estudo:
Clinical_trials
Limite:
Adult
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Humans
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Male
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article