Daley Joseph C, Hogeman Cynthia S, Sinoway Lawrence I
Division of Pulmonary Allergy and Critical Care, The Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey 17033, USA.
Am J Physiol Regul Integr Comp Physiol. 2002 Jun;282(6):R1608-12. doi: 10.1152/ajpregu.00370.2001.
Increases in the concentration of interstitial potassium concentration during exercise may play a role in the modulation of the cardiovascular response to exercise. However, it is not known if changes in potassium correlate with indexes of muscle reflex engagement. Eight healthy subjects performed dynamic [rhythmic handgrip (RHG)] and static handgrip (SHG) exercise at 40% of maximal voluntary contraction. Forearm circulatory arrest was performed to assess the metaboreceptor component of the exercise pressor reflex. Mean arterial pressure (MAP) and muscle sympathetic nerve activity (MSNA) were measured during each exercise paradigm. Venous plasma potassium concentrations (K(+)) were measured and used as a surrogate marker for interstitial potassium. K(+) were measured at baseline and at 1-min intervals during dynamic handgrip. During SHG, K(+) were measured at baseline, 30 and 90 s of exercise, and twice during forearm circulatory arrest. Mean K(+) was 3.6 mmol/l at rest before both paradigms. During RHG, K(+) rose by approximately 1.0 mmol/l by min 2 and remained constant throughout the rest of handgrip. During SHG, K(+) rose significantly at 30 s and rose an additional approximately 1.0 mmol/l by peak exercise. MAP and MSNA rose during both exercise paradigms. During posthandgrip circulatory arrest (PHG-CA), MSNA and blood pressure remained above baseline. K(+) and MSNA did not correlate during either exercise paradigm. Moreover, during PHG-CA, there was clear dissociation of MSNA from K(+). These data suggest that potassium does not play a direct role in the maintenance of the exercise pressor reflex.
运动期间间质钾浓度的升高可能在调节心血管对运动的反应中发挥作用。然而，尚不清楚钾的变化是否与肌肉反射参与指标相关。八名健康受试者以最大自主收缩的40%进行动态[节律性握力（RHG）]和静态握力（SHG）运动。进行前臂循环阻断以评估运动升压反射的代谢感受器成分。在每种运动模式期间测量平均动脉压（MAP）和肌肉交感神经活动（MSNA）。测量静脉血浆钾浓度（[K⁺]V）并将其用作间质钾的替代标志物。在动态握力期间，在基线和每隔1分钟测量一次[K⁺]V。在SHG期间，在基线、运动30秒和90秒时以及在前臂循环阻断期间测量两次[K⁺]V。在两种模式之前的静息状态下，平均[K⁺]V为3.6 mmol/L。在RHG期间，[K⁺]V在第2分钟时升高约1.0 mmol/L，并在握力的其余时间保持恒定。在SHG期间，[K⁺]V在30秒时显著升高，并在运动峰值时再升高约1.0 mmol/L。在两种运动模式期间，MAP和MSNA均升高。在握力后循环阻断（PHG-CA）期间，MSNA和血压保持在基线以上。在任何一种运动模式期间，[K⁺]V与MSNA均无相关性。此外，在PHG-CA期间，MSNA与[K⁺]V明显分离。这些数据表明钾在运动升压反射的维持中不发挥直接作用。
