Role of cardiac output versus peripheral vasoconstriction in mediating muscle metaboreflex pressor responses: dynamic exercise versus postexercise muscle ischemia
| Autor: | Matthew Coutsos, Donal S. O'Leary, Jasdeep Kaur, Robert A. Augustyniak, Marty D. Spranger, Javier A. Sala-Mercado, Doug Stayer |
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| Rok vydání: | 2013 |
| Předmět: |
Male
medicine.medical_specialty Mean arterial pressure Cardiac output Physiology Physical Exertion Baroreflex Ventricular Function Left Dogs Heart Rate Ischemia Physiology (medical) Internal medicine Reflex Heart rate medicine Animals Arterial Pressure Cardiac Output Muscle Skeletal Neural Control business.industry food and beverages Stroke Volume Stroke volume Hindlimb Blood pressure Regional Blood Flow Vasoconstriction Data Interpretation Statistical Anesthesia Cardiology Female medicine.symptom business |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 304:R657-R663 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.00601.2012 |
| Popis: | Muscle metaboreflex activation (MMA) during submaximal dynamic exercise in normal individuals increases mean arterial pressure (MAP) via increases in cardiac output (CO) with little peripheral vasoconstriction. The rise in CO occurs primarily via increases in heart rate (HR) with maintained or slightly increased stroke volume. When the reflex is sustained during recovery (postexercise muscle ischemia, PEMI), HR declines yet MAP remains elevated. The role of CO in mediating the pressor response during PEMI is controversial. In seven chronically instrumented canines, steady-state values with MMA during mild exercise (3.2 km/h) were observed by reducing hindlimb blood flow by ∼60% for 3–5 min. MMA during exercise was followed by 60 s of PEMI. Control experiments consisted of normal exercise and recovery. MMA during exercise increased MAP, HR, and CO by 55.3 ± 4.9 mmHg, 42.5 ± 6.9 beats/min, and 2.5 ± 0.4 l/min, respectively. During sustained MMA via PEMI, MAP remained elevated and CO remained well above the normal recovery levels. Neither MMA during dynamic exercise nor during PEMI significantly affected peripheral vascular conductance. We conclude that the sustained increase in MAP during PEMI is driven by a sustained increase in CO not peripheral vasoconstriction. |
| Databáze: | OpenAIRE |
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