Murai Hisayoshi, Takamura Masayuki, Maruyama Michirou, Nakano Manabu, Ikeda Tatsunori, Kobayashi Daisuke, Otowa Kan-ichi, Ootsuji Hiroshi, Okajima Masaki, Furusho Hiroshi, Takata Shigeo, Kaneko Shuichi
Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.
J Physiol. 2009 Jun 1;587(Pt 11):2613-22. doi: 10.1113/jphysiol.2009.172627. Epub 2009 Apr 29.
Sympathetic activation in chronic heart failure (CHF) is greatly augmented at rest but the response to exercise remains controversial. We previously demonstrated that single-unit muscle sympathetic nerve activity (MSNA) provides a more detailed description of the sympathetic response to physiological stress than multi-unit nerve recordings. The purpose of this study was to determine whether the reflex response and discharge properties of single-unit MSNA are altered during handgrip exercise (HG, 30% of maximum voluntary contraction for 3 min) in CHF patients (New York Heart Association functional class II or III, n = 16) compared with age-matched healthy control subjects (n = 13). At rest, both single-unit and multi-unit indices of sympathetic outflow were augmented in CHF compared with controls (P < 0.05). However, the percentage of cardiac intervals that contained one, two, three or four single-unit spikes were not different between the groups. Compared to the control group, HG elicited a larger increase in multi-unit total MSNA (Delta1002 +/- 50 compared with Delta636 +/- 76 units min(-1), P < 0.05) and single-unit MSNA spike incidence (Delta27 +/- 5 compared with Delta8 +/- 2 spikes (100 heart beats)(-1)), P < 0.01) in the CHF patients. More importantly, the percentage of cardiac intervals that contained two or three single-unit spikes was increased (P < 0.05) during exercise in the CHF group only (Delta8 +/- 2% and Delta5 +/- 1% for two and three spikes, respectively). These results suggest that the larger multi-unit total MSNA response observed during HG in CHF is brought about in part by an increase in the probability of multiple firing of single-unit sympathetic neurones.
慢性心力衰竭（CHF）患者在静息状态下交感神经激活显著增强，但运动时的反应仍存在争议。我们之前证明，与多单位神经记录相比，单单位肌肉交感神经活动（MSNA）能更详细地描述交感神经对生理应激的反应。本研究的目的是确定与年龄匹配的健康对照受试者（n = 13）相比，CHF患者（纽约心脏协会功能分级II或III级，n = 16）在进行握力运动（HG，最大自主收缩的30%，持续3分钟）时，单单位MSNA的反射反应和放电特性是否发生改变。静息时，与对照组相比，CHF患者交感神经输出的单单位和多单位指标均增强（P < 0.05）。然而，两组间包含一个、两个、三个或四个单单位尖峰的心动周期百分比并无差异。与对照组相比，HG引起CHF患者多单位总MSNA的增加幅度更大（分别为Delta1002 +/- 50与Delta636 +/- 76单位·分钟(-1)，P < 0.05）以及单单位MSNA尖峰发生率更高（分别为Delta27 +/- 5与Delta8 +/- 2尖峰·(100次心跳)(-1)，P < 0.01）。更重要的是，仅在CHF组运动期间，包含两个或三个单单位尖峰的心动周期百分比增加（P < 0.05）（两个尖峰时分别为Delta8 +/- 2%，三个尖峰时为Delta5 +/- 1%）。这些结果表明，CHF患者在HG期间观察到的多单位总MSNA反应增强部分是由于单单位交感神经元多重放电概率增加所致。
