Muscle metaboreflex attenuates spontaneous heart rate baroreflex sensitivity during dynamic exercise
Open Access
- 1 June 2007
- journal article
- Published by American Physiological Society in American Journal of Physiology-Heart and Circulatory Physiology
- Vol. 292 (6), H2867-H2873
- https://doi.org/10.1152/ajpheart.00043.2007
Abstract
Hypoperfusion of active skeletal muscle elicits a reflex pressor response termed the muscle metaboreflex. Dynamic exercise attenuates spontaneous baroreflex sensitivity (SBRS) in the control of heart rate (HR) during rapid, spontaneous changes in blood pressure (BP). Our objective was to determine whether muscle metaboreflex activation (MRA) further diminishes SBRS. Conscious dogs were chronically instrumented for measurement of HR, cardiac output, mean arterial pressure, and left ventricular systolic pressure (LVSP) at rest and during mild (3.2 km/h) or moderate (6.4 km/h at 10% grade) dynamic exercise before and after MRA (via partial reduction of hindlimb blood flow). SBRS was evaluated as the slopes of the linear relations (LRs) between HR and LVSP during spontaneous sequences of at least three consecutive beats when HR changed inversely vs. pressure (expressed as beats·min−1·mmHg−1). During mild exercise, these LRs shifted upward, with a significant decrease in SBRS (−3.0 ± 0.4 vs. −5.2 ± 0.4, P < 0.05 vs. rest). MRA shifted LRs upward and rightward and decreased SBRS (−2.1 ± 0.1, P < 0.05 vs. mild exercise). Moderate exercise shifted LRs upward and rightward and significantly decreased SBRS (−1.2 ± 0.1, P < 0.05 vs. rest). MRA elicited further upward and rightward shifts of the LRs and reductions in SBRS (−0.9 ± 0.1, P < 0.05 vs. moderate exercise). We conclude that dynamic exercise resets the arterial baroreflex to higher BP and HR as exercise intensity increases. In addition, increases in exercise intensity, as well as MRA, attenuate SBRS.Keywords
This publication has 64 references indexed in Scilit:
- Time-dependent modulation of arterial baroreflex control of muscle sympathetic nerve activity during isometric exercise in humansAmerican Journal of Physiology-Heart and Circulatory Physiology, 2006
- Altered muscle metaboreflex control of coronary blood flow and ventricular function in heart failureAmerican Journal of Physiology-Heart and Circulatory Physiology, 2005
- Neural mechanisms of cardiovascular regulation during exerciseAutonomic Neuroscience, 2001
- Severe exercise alters the strength and mechanisms of the muscle metaboreflex.American Journal of Physiology-Heart and Circulatory Physiology, 2001
- Alteration of humoral and peripheral vascular responses during graded exercise in heart failureJournal of Applied Physiology, 2001
- Heart failure alters the strength and mechanisms of the muscle metaboreflexAmerican Journal of Physiology-Heart and Circulatory Physiology, 2000
- Dynamic exercise shifts the operating point and reduces the gain of the arterial baroreflex in ratsAmerican Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 1998
- Characteristics of the carotid baroreflex in man during normal and flow‐restricted exerciseActa Physiologica Scandinavica, 1992
- Onset of exercise shifts operating point of arterial baroreflex to higher pressuresAmerican Journal of Physiology-Heart and Circulatory Physiology, 1992
- Evaluation of baroreceptor reflex by blood pressure monitoring in unanesthetized catsAmerican Journal of Physiology-Heart and Circulatory Physiology, 1988