Crisafulli Antonio, Salis Enrico, Pittau Gianluigi, Lorrai Luigi, Tocco Filippo, Melis Franco, Pagliaro Pasquale, Concu Alberto
Dept. of Science Applied to Biological Systems, University of Cagliari, 09124 Cagliari, Italy.
Am J Physiol Heart Circ Physiol. 2006 Dec;291(6):H3035-42. doi: 10.1152/ajpheart.00221.2006. Epub 2006 Jun 16.
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.
骨骼肌内代谢终产物的蓄积会刺激感觉神经，从而引发一种称为“代谢反射”的升压反应。本研究的目的是评估在两种不同运动强度后通过运动后肌肉缺血（PEMI）激活代谢反射期间发生的血流动力学变化。在12名健康受试者中，在从初步测试中达到的最大工作量的30%（PEMI 30%）和70%（PEMI 70%）强度进行的单腿动态膝关节伸展恢复开始时，采用PEMI方法研究代谢反射。还进行了相同强度的对照运动恢复测试。通过阻抗心动图评估中心血流动力学。主要发现为：1）在代谢反射期间，与较高工作量对抗的运动比与较低工作量对抗的运动导致更明显的血压升高；2）在PEMI 70%期间，这种血压反应主要通过增强心肌收缩力来实现，心肌收缩力增加了每搏输出量，进而增加了心输出量，而在PEMI 30%期间，血压反应主要通过血管收缩来实现。因此，仅在PEMI 70%测试中达到了心肌收缩力的显著增强。这些结果表明，PEMI在人类中引起的代谢反射参与期间的血流动力学调节取决于先前运动的强度。此外，代谢反射期间的心血管反应不仅仅通过血管收缩单独实现，似乎外周血管收缩和心脏收缩力募集之间存在复杂的相互作用。
