Seals D R, Johnson D G, Fregosi R F
Department of Exercise and Sport Sciences, Arizona Health Sciences Center, University of Arizona, Tucson 85721.
Am J Physiol. 1991 May;260(5 Pt 2):R873-8. doi: 10.1152/ajpregu.1991.260.5.R873.
The primary aim of this study was to determine the influence of systemic hyperoxia on sympathetic nervous system behavior at rest and during submaximal exercise in humans. In seven healthy subjects (aged 19-31 yr) we measured postganglionic sympathetic nerve activity to skeletal muscle (MSNA) in the leg, antecubital venous norepinephrine concentrations, heart rate, and arterial blood pressure during normoxic rest (control) followed by 3- to 4-min periods of either hyperoxic (100% O2 breathing) rest, normoxic exercise (rhythmic handgrips at 50% of maximum force), or hyperoxic exercise. During exercise, isocapnia was maintained by adding CO2 to the inspirate as necessary. At rest, hyperoxia lowered MSNA burst frequency (12-42%) and total activity (6-42%) in all subjects; the average reductions were 25 and 23%, respectively (P less than 0.05 vs. control). Heart rate also decreased during hyperoxia (6 +/- 1 beats/min, P less than 0.05), but arterial blood pressure was not affected. During hyperoxic compared with normoxic exercise, there were no differences in the magnitudes of the increases in MSNA burst frequency or total activity, plasma norepinephrine concentrations, or mean arterial blood pressure. In contrast, the increase in heart rate during hyperoxic exercise (13 +/- 2 beats/min) was less than the increase during normoxic exercise (20 +/- 2 beats/min; P less than 0.05). We conclude that, in healthy humans, systemic hyperoxia 1) lowers efferent sympathetic nerve activity to skeletal muscle under resting conditions without altering venous norepinephrine concentrations and 2) has no obvious modulatory effect on the nonactive muscle sympathetic nerve adjustments to rhythmic exercise.
本研究的主要目的是确定全身高氧对人体静息状态及次最大运动时交感神经系统活动的影响。我们对7名健康受试者（年龄19 - 31岁）进行了测量，在常氧静息（对照）状态下，随后依次进行3 - 4分钟的高氧（吸入100%氧气）静息、常氧运动（以最大力量的50%进行有节奏的握力运动）或高氧运动，期间测量腿部骨骼肌节后交感神经活动（MSNA）、肘前静脉去甲肾上腺素浓度、心率和动脉血压。运动期间，必要时通过向吸入气体中添加二氧化碳来维持等碳酸血症。静息时，高氧降低了所有受试者的MSNA爆发频率（12% - 42%）和总活动量（6% - 42%）；平均降低幅度分别为25%和23%（与对照相比，P < 0.05）。高氧期间心率也降低（6 ± 1次/分钟，P < 0.05），但动脉血压未受影响。与常氧运动相比，高氧运动时MSNA爆发频率或总活动量、血浆去甲肾上腺素浓度或平均动脉血压升高的幅度没有差异。相反，高氧运动期间心率的升高（13 ± 2次/分钟）小于常氧运动期间的升高（20 ± 2次/分钟；P < 0.05）。我们得出结论，在健康人体中，全身高氧1）在静息状态下降低了骨骼肌的传出交感神经活动，而不改变静脉去甲肾上腺素浓度，2）对有节奏运动时非活动肌肉的交感神经调节没有明显的调节作用。
