EFFECTS OF BEDREST ON FOREARM MUSCLE REFLEXES

这个项目的总体目标是检查两周卧床休息对前臂有节奏和静态运动的交感神经反应的影响。我们推测，交感神经反应将增加，因为乳酸的产生和前臂间质体积将增加。我们进一步假设，前臂握力练习和/或间歇性前臂压缩将作为消除卧床休息影响的对策。在项目的第一年，我们将检查卧床休息对交感神经反应的影响：静态运动，节律性前臂运动和不自主的二头肌收缩。由于静态运动中交感神经放电的增加主要是由于代谢物受体的兴奋，因此静态运动中的实验将有助于确定卧床休息是否增强了代谢物受体的活性。将进行有节奏的前臂锻炼实验，以检验卧床休息是否增加了机械直肌活动和/或中枢指挥活动。我们将进行二头肌非自主收缩的实验，以确定人类前臂机械敏感的传入神经是否会因卧床休息2周而变得敏感。将使用最先进的人体生理学技术，包括显微神经学和核磁共振。

The overall objectives of this project are to examine the effects of 2 weeks of bed rest on the sympathetic nerve responses to rhythmic and static forearm exercise. We postulate that sympathetic nerve responses will be increased because lactic acid production and forearm interstitial volume will be increased. We further postulate that forearm handgrip exercise and/or intermittant forearm compression will act as countermeasures to obviate the effects of bedrest. In the first year of the project, we will examine the effects of bedrest on the sympathetic nerve responses to: static exercises, rythmic forearm exercise and involuntary biceps contraction. Since increases in sympathetic discharge during static exercise are predominantly due to excitation of metaboreceptors, the experiments in static exercise will help determine if metaboreceptor activity is enhanced by bedrest. Experiments in rhythmic forearm exercise will be performed to examine whether mechanorecptor activity and/or central command activity is augmented by bedrest. The experiments in involuntary bicep contraction will be performed to determine whether mechanically-sensitive afferents in the human forearm are sensitized by the 2 week period of bedrest. State of the art human physiology techniques including microneurography and NMR will be used.