Mechanisms Underlying Exaggerated Metaboreflex Activation in Prehypertensive Men
Mechanisms Underlying Exaggerated Metaboreflex Activation in Prehypertensive Men
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DOI：
10.1249/mss.0000000000000573
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发表时间：
2015-08-01
影响因子：
4.1
通讯作者：
Kim, Jong-Kyung
中科院分区：
文献类型：
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作者：
Kim, Kyung-Ae;Stebbins, Charles L.;Kim, Jong-Kyung
目的以前，我们发现高血压前期肌肉代谢反射激活的升压反应增强，并与外周血管收缩有关。然而，这种夸张反应的机制尚不清楚。因此，我们测试了这一假设，即由于肌肉代谢产物的产生增加，这种反射的激活被增强（即，方法对22名男性（11名正常血压和11名高血压前期）进行了研究。比较两组在静态运动（SE）和运动后肌肉缺血（PEMI）时心输出量（Q）、平均动脉压（MAP）和总外周阻力（TPR）的变化。受试者在50%最大自主收缩（MVC）下完成2分钟SE，然后进行2分钟PEMI。测定代谢产物和激素（儿茶酚胺，血管加压素，血浆肾素活性）的静脉血样分别取自运动和nonexercising arm. ResultsSE（39 +/- 3与31 +/- 2毫米汞柱）和PEMI（24 +/- 3与19 +/- 3毫米汞柱）的平均动脉压反应显着较高的高血压前期组。在PEMI期间，两组均观察到乳酸盐升高和pH值降低。然而，这些变量的变化在高血压前期组中更大（乳酸，50.1 +/- 6.2 vs 32.8 +/- 7.6 mg中心点dL（-1）; pH，-0.06 +/- 0.02 vs -0.01 +/- 0.01）（P < 0.05）。运动后肌肉缺血并没有引起增加激素在任何group. Conclusions相比，血压正常组，在高血压前期组，对代谢反射的升压反应增强与肌肉代谢产物的产生有关，这些代谢产物激活其传入臂。血管紧张素系统和交感神经系统的更大激活并不明显。因此，高血压前期的其他特定因素，如动脉硬化，可能已经参与。
PurposePreviously, we found that the pressor response to muscle metaboreflex activation is enhanced in prehypertension and associated with peripheral vasoconstriction. However, mechanisms underlying this exaggerated response are not clear. Therefore, we tested the hypothesis that activation of this reflex is augmented owing to increased production of muscle metabolites (i.e., lactate, K+, and H+).MethodsTwenty-two men (11 normotensive and 11 prehypertensive) were studied. Changes in cardiac output (Q), mean arterial pressure (MAP), and total peripheral resistance (TPR) were compared between the two groups during static exercise (SE) and postexercise muscular ischemia (PEMI). Subjects completed 2 min of SE at 50% of maximal voluntary contraction (MVC) followed by 2 min of PEMI. Venous blood samples for determination of metabolites and hormones (catecholamines, vasopressin, and plasma renin activity) were taken from the exercising and nonexercising arm, respectively.ResultsMean arterial pressure responses to SE (39 +/- 3 vs 31 +/- 2 mm Hg) and PEMI (24 +/- 3 vs 19 +/- 3 mm Hg) were significantly higher in the prehypertensive group. Increases in lactate and decreases in pH during PEMI were seen in both groups. However, changes in these variables were greater in the prehypertensive group (lactate, 50.1 +/- 6.2 vs 32.8 +/- 7.6 mg center dot dL(-1); pH, -0.06 +/- 0.02 vs -0.01 +/- 0.01) (P < 0.05). Postexercise muscular ischemia did not evoke increases in hormones in either group.ConclusionsCompared to the normotensive group, the augmented pressor response to the metaboreflex in the prehypertensive group was associated with greater production of muscle metabolites that activate its afferent arm. The augmented response was not associated with activation of the vasopressin and renin-angiotensin systems and greater activation of the sympathetic nervous system was not apparent. Consequently, additional factors specific to prehypertension, such as arterial stiffness, may have been involved.