Modulation of cardiac contractility by muscle metaboreflex following efforts of different intensities in humans
Modulation of cardiac contractility by muscle metaboreflex following efforts of different intensities in humans
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DOI：
10.1152/ajpheart.00221.2006
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发表时间：
2006-12-01
影响因子：
4.8
通讯作者：
Concu, Alberto
中科院分区：
文献类型：
--
作者：
Crisafulli, Antonio;Salis, Enrico;Concu, Alberto
代谢终末产物在骨骼肌内的积累刺激感觉神经，从而引起一种称为“代谢反射”的升压反应。本研究的目的是评价两种不同强度的运动后肌肉缺血(PEMI)引起的代谢性反射激活过程中血流动力学的变化。在12名健康受试者中，用PEMI方法研究了恢复开始时的代谢性反射--在初步测试中达到最大负荷的30%(PEMI 30%)和70%(PEMI 70%)的强度下进行动态膝关节伸展。还进行了相同强度的对照运动恢复测试。用心阻抗图评价中枢血流动力学。主要研究结果是：1)在代谢反射中，针对较高负荷进行的运动引起的血压升高比针对较低负荷进行的运动引起的血压升高更为显著；2)在PEMI 70%期间，这种血压反应主要是通过增强心肌收缩能力来实现的，从而增加每搏输出量，进而增加心输出量，而在PEMI 30%期间，血压反应主要是通过血管收缩实现的。因此，只有在PEMI 70%测试中才能达到心肌收缩能力的显著增强。这些结果表明，在由PEMI引起的人体代谢性反射参与过程中的血流动力学调节依赖于先前努力的强度。此外，代谢性反射中的心血管反应不仅仅是通过血管收缩实现的，而且似乎在外周血管收缩和心脏收缩能力恢复之间存在复杂的相互作用。
Accumulation of metabolic end products within skeletal muscle stimulates sensory nerves, thus evoking a pressor response termed "metaboreflex." The aim of this study was to evaluate changes in hemodynamics occurring during metaboreflex activation obtained by postexercise muscle ischemia (PEMI) after two different exercise intensities. In twelve healthy subjects, the metaboreflex was studied with the PEMI method at the start of recovery from one leg-dynamic knee extension performed at intensities of 30% (PEMI 30%) and 70% (PEMI 70%) of the maximum workload achieved in a preliminary test. Control exercise recovery tests at the same intensities were also conducted. Central hemodynamics were evaluated by means of impedance cardiography. The main findings were that 1) during metaboreflex, exercise conducted against the higher workload caused a more pronounced blood pressure increase than the strain conducted against the lower workload; and 2) during PEMI 70%, this blood pressure response was mainly achieved through enhancement of myocardial contractility that increased stroke volume and, in turn, cardiac output, whereas during PEMI 30%, the blood pressure response was reached predominantly by means of vasoconstriction. Thus a substantial enhancement of myocardial contractility was reached only in the PEMI 70% test. These results suggest that hemodynamic regulation during metaboreflex engagement caused by PEMI in humans is dependent on the intensity of the previous effort. Moreover, the cardiovascular response during metaboreflex is not merely achieved by vasoconstriction alone, but it appears that there is a complex interplay between peripheral vasoconstriction and heart contractility recruitment.