Progressive muscle metaboreflex activation gradually decreases spontaneous heart rate baroreflex sensitivity during dynamic exercise.
Progressive muscle metaboreflex activation gradually decreases spontaneous heart rate baroreflex sensitivity during dynamic exercise.
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动态运动期间，渐进性肌肉代谢反射激活逐渐降低自发心率压力反射敏感性。
DOI：
10.1152/ajpheart.00908.2009
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
O'Leary,DonalS
中科院分区：
文献类型：
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作者：
Sala-Mercado,JavierA;Ichinose,Masashi;Coutsos,Matthew;Li,Zhenhua;Fano,Dominic;Ichinose,Tomoko;Dawe,ElizabethJ;O'Leary,DonalS
活跃骨骼肌缺血引起一种称为肌肉代谢反射的压力反应。我们验证了在正常狗进行动态运动时，分级肌肉代谢反射激活（MMA）会逐渐减弱自发心率压力反射敏感性（SBRS）的假设。在进行性MMA之前和期间，通过渐进式后肢血流量（HLBF）的逐渐减少，长期测量动物在休息时和轻度或中度跑步机运动时的心率（HR）、心输出量（CO）、平均动脉压和收缩压（MAP和SAP）以及左心室收缩压（LVSP）。在轻度运动时，SBRS（心率与血压成反比时，心率与LVSP或SAP之间的线性关系斜率）较静息值（- 5.56±0.86 vs - 2.67±0.50次·min - 1·mmHg - 1，P<0.05）下降，且LRs向上移动。渐进式MMA逐渐线性增加MAP、CO和HR；SBRS线性降低；并将LRs向上和向右移动到更高的HR和压力，这表明气压反射重置。适度运动导致SBRS显著降低（- 1.57±0.38次·min - 1·mmHg - 1，P<0.05），并出现向上和向右复位。在这种较高的工作负荷下，逐渐的MMA也导致MAP、CO和HR的显著逐渐增加，SBRS的逐渐减少，并且LRs向更高的MAP和HR转移。我们的研究结果表明，在轻度和中度动态运动中，逐渐的MMA会逐渐降低SBRS。此外，血压的压力反射控制逐渐重置为血压和心率的升高，与MMA的程度成比例。
Ischemia of active skeletal muscle elicits a pressor response termed the muscle metaboreflex. We tested the hypothesis that in normal dogs during dynamic exercise, graded muscle metaboreflex activation (MMA) would progressively attenuate spontaneous heart rate baroreflex sensitivity (SBRS). The animals were chronically instrumented to measure heart rate (HR), cardiac output (CO), mean and systolic arterial pressure (MAP and SAP), and left ventricular systolic pressures (LVSP) at rest and during mild or moderate treadmill exercise before and during progressive MMA [via graded reductions of hindlimb blood flow (HLBF)]. SBRS [slopes of the linear relationships (LRs) between HR and LVSP or SAP during spontaneous sequences of ≥3 consecutive beats when HR changed inversely vs. pressure] decreased during mild exercise from the resting values (−5.56 ± 0.86 vs. −2.67 ± 0.50 beats·min−1·mmHg−1,P<0.05), and in addition, these LRs were shifted upward. Progressive MMA gradually and linearly increased MAP, CO, and HR; linearly decreased SBRS; and shifted LRs upward and rightward to higher HR and pressures denoting baroreflex resetting. Moderate exercise caused a substantial reduction in SBRS (−1.57 ± 0.38 beats·min−1·mmHg−1,P<0.05) and both an upward and rightward resetting. Gradual MMA at this higher workload also caused significant progressive increases in MAP, CO, and HR and progressive decreases in SBRS, and the LRs were shifted to higher MAP and HR. Our results demonstrate that gradual MMA during mild and moderate dynamic exercise progressively decreases SBRS. In addition, baroreflex control of HR is progressively reset to higher blood pressure and HR in proportion to the extent of MMA.