Spectral analysis of muscle sympathetic nerve activity in heat-stressed humans

被引:30
作者
Cui, J
Zhang, R
Wilson, TE
Crandall, CG
机构
[1] Presbyterian Med Ctr, Inst Exercise & Environm Med, Dallas, TX 75231 USA
[2] Univ Texas, SW Med Ctr, Dept Internal Med, Dallas, TX 75390 USA
来源
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY | 2004年 / 286卷 / 03期
关键词
sympathetic nervous system; autonomic; cardiovascular; variability;
D O I
10.1152/ajpheart.00790.2003
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Whole body heating increases muscle sympathetic nerve activity (MSNA); however, the effect of heat stress on spectral characteristics of MSNA is unknown. Such information may provide insight into mechanisms of heat stress-induced MSNA activation. The purpose of the present study was to test the hypothesis that heat stress-induced changes in systolic blood pressure variability parallel changes in MSNA variability. In 13 healthy subjects, MSNA, electrocardiogram, arterial blood pressure (via Finapres), and respiratory activity were recorded under both normothermic and heat stress conditions. Spectral characteristics of integrated MSNA, R-R interval, systolic blood pressure, and respiratory excursions were assessed in the low (LF; 0.03-0.15 Hz) and high (HF; 0.15-0.45 Hz) frequency components. Whole body heating significantly increased skin and core body temperature, MSNA burst rate, and heart rate, but not mean arterial blood pressure. Systolic blood pressure and R-R interval variability were significantly reduced in both the LF and HF ranges. Compared with normothermic conditions, heat stress significantly increased the HF component of MSNA, while the LF component of MSNA was not altered. Thus the LF-to-HF ratio of MSNA oscillatory components was significantly reduced. These data indicate that the spectral characteristics of MSNA are altered by whole body heating; however, heat stress-induced changes in MSNA do not parallel changes in systolic blood pressure variability. Moreover, the reduction in LF component of systolic blood pressure during heat stress is unlikely related to spectral changes in MSNA.
引用
收藏
页码:H1101 / H1106
页数:6
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