Attenuated muscle metaboreflex-induced increases in cardiac function in hypertension
| Autor: | Marty D. Spranger, Donal S. O'Leary, Matthew Coutsos, Rania Abu-Hamdah, Robert A. Augustyniak, Douglas Stayer, Javier A. Sala-Mercado, Jasdeep Kaur |
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| Rok vydání: | 2013 |
| Předmět: |
Cardiac function curve
Mean arterial pressure medicine.medical_specialty Cardiac output Sympathetic Nervous System Time Factors Physiology Physical Exertion Exercise intolerance Ventricular Function Left Sudden cardiac death Running Dogs Integrative Cardiovascular Physiology and Pathophysiology Physiology (medical) Internal medicine Reflex medicine Animals Arterial Pressure Cardiac Output Muscle Skeletal Exercise Tolerance business.industry Hemodynamics Heart medicine.disease Myocardial Contraction Disease Models Animal Blood pressure medicine.anatomical_structure Pathophysiology of hypertension Anesthesia Hypertension Vascular resistance Cardiology Female Vascular Resistance medicine.symptom Cardiology and Cardiovascular Medicine business Muscle Contraction |
| Zdroj: | American journal of physiology. Heart and circulatory physiology. 305(10) |
| ISSN: | 1522-1539 |
| Popis: | Sympathoactivation may be excessive during exercise in subjects with hypertension, leading to increased susceptibility to adverse cardiovascular events, including arrhythmias, infarction, stroke, and sudden cardiac death. The muscle metaboreflex is a powerful cardiovascular reflex capable of eliciting marked increases in sympathetic activity during exercise. We used conscious, chronically instrumented dogs trained to run on a motor-driven treadmill to investigate the effects of hypertension on the mechanisms of the muscle metaboreflex. Experiments were performed before and 30.9 ± 4.2 days after induction of hypertension, which was induced via partial, unilateral renal artery occlusion. After induction of hypertension, resting mean arterial pressure was significantly elevated from 98.2 ± 2.6 to 141.9 ± 7.4 mmHg. The hypertension was caused by elevated total peripheral resistance. Although cardiac output was not significantly different at rest or during exercise after induction of hypertension, the rise in cardiac output with muscle metaboreflex activation was significantly reduced in hypertension. Metaboreflex-induced increases in left ventricular function were also depressed. These attenuated cardiac responses caused a smaller metaboreflex-induced rise in mean arterial pressure. We conclude that the ability of the muscle metaboreflex to elicit increases in cardiac function is impaired in hypertension, which may contribute to exercise intolerance. |
| Databáze: | OpenAIRE |
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