摘要
低压值下体负压(LBNP)可仅使心肺压力感受器卸荷。采用-2kPaLBNP实验结果表明:LBNP既不引起动脉血压变化,也不引起心率改变,但却引起基础胸阻抗(Z。)从对照的21.8±0.4升高到22.5±0.5Ω(P<0.01),前臂血管阻力(FVR)从12.3±0.9升高到19.9±1.4U(P<0.01),前臂血流(FBF)从对照时7.1±0.5降低到4.3±0.3ml·min ̄(-1)·100ml ̄(-1),心率变异性谱(HRV)未发生任何变化,即心肺压力感受器卸荷时心脏自主神经活动水平与均衡性不受影响。由于FVR和FBF的变化可间接反映外周血管交感传出活动水平,上述实验结果提示,心肺压力感受器对外周血管及心脏自主神经活动的调节可能存在机能分化现象。
Twelve healthy young male subjects underwent a 10min control period followed by 20min of-2kPa lower body negative pressure(LBNP).During this low level of LBNP,there was no anysignificant change in arterial blood pressure and heart rate. Baseline thoracic impedance(Z_O) in-creased from a control value of 21.8 ± 0.4 to 22.5 ± 0.5Ω(P<0.01),the forearm blood flow (FBF)decreased from 7.1 ± 0.5 to 4.3 ± 0.3ml·min ̄(-1)·100ml ̄(-1)(P<0.01)and the forearm vascular re-sistance(FVR) increased from 12.3 ± 0.9 to 19.9±1.4 units(P<0.01).However,changes ofheart rate variability(HRV)spectral components during-2kPa LBNP exposure were not ob-served.These observations demonstrate that sustained unloading of cardiopulmonarybaroreceptors has no effect on cardiac sympathetic and parasympathetic nerve activities.To ourknowledge,the changes in muscle sympathetic nerve activity(MSNA) may be in parallel to thatof FVR,therefore it is suggested that a functional dissociation of cardiopulmonary baroreceptorregulation on MSNA and cardiac autonomic function may exist in humans.
出处
《中国应用生理学杂志》
CSCD
1995年第4期309-312,共4页
Chinese Journal of Applied Physiology
关键词
下体负压
心肺压力感受器
心率变异性
lower body negative pressure
cardiopulmonary baroreceptor
heart rate variability
cardiovascular autonomic regulation