Abstract：
Harmful health effects of exposure to low-frequency noise (LFN) defined as noise with frequencies at ≤100 Hz on the circulatory system have been a concern. However, there has been no study on the effects of exposure to LFN on the circulatory system with consideration of its frequencies and decibels. In this study, the effects of short-term exposure to broad-band LFNs and their pure-tone components (pure-tone LFNs) on cutaneous blood flow in the extremities including the hands were investigated. In our fieldwork study, we first sampled some kinds of common broad-band LFNs. Our human study then showed that broad-band LFN with a narrower frequency range more strongly increased cutaneous blood flow than did broad-band LFN with a wider frequency range. Pure-tone LFNs of 70-100 Hz at ≤85 dB(Z), but not pure-tone LFNs exceeding 100 Hz, further increased levels of cutaneous blood flow. Our wavelet-transform spectrum analysis of cutaneous blood flow next revealed that the nitric oxide (NO)-dependent and -independent vascular activities of the vascular endothelium were specifically increased by exposure to pure-tone LFN. Our animal study again indicated that exposure to pure-tone LFN increased cutaneous blood flow in mice with impairments of bilateral inner ears as well as cutaneous blood flow in control mice, suggesting a limited effect of inner ear function on the LFN-mediated increase in cutaneous blood flow. The NO-dependent suppressive effect of pure-tone LFN on cutaneous blood flow was confirmed by inhibition of vascular endothelial activity through intravenous injection of an NO inhibitor in wild-type mice. Taken together, the results of this study demonstrated that the vascular endothelium is a target tissue of LFN and that NO is an effector of the LFN-mediated increase in cutaneous blood flow. Since improvement of peripheral circulation could generally promote human health, short-term exposure to LFN may be beneficial for health.
摘要：
暴露于低频噪声（LFN）对循环系统中频率≤100Hz的噪声的有害健康影响一直是人们关注的问题。然而,没有关于暴露于LFN对循环系统的影响的研究，同时考虑其频率和分贝。在这项研究中,研究了短期暴露于宽带LFN及其纯音成分（纯音LFN）对包括手部在内的四肢皮肤血流的影响。在我们的实地考察中,我们首先采样了几种常见的宽带LFN。然后，我们的人体研究表明，频率范围较窄的宽带LFN比频率范围较宽的宽带LFN更强烈地增加皮肤血流量。在≤85dB(Z)时70-100Hz的纯音LFN，但纯音LFN不超过100Hz，皮肤血流量水平进一步增加。接下来，我们对皮肤血流的小波变换频谱分析显示，暴露于纯音LFN会特别增加血管内皮的一氧化氮（NO）依赖性和非依赖性血管活性。我们的动物研究再次表明，暴露于纯音LFN会增加双侧内耳受损的小鼠的皮肤血流量以及对照小鼠的皮肤血流量，提示内耳功能对LFN介导的皮肤血流量增加的影响有限。纯音LFN对皮肤血流的NO依赖性抑制作用通过在野生型小鼠中静脉注射NO抑制剂来抑制血管内皮活性来证实。一起来看,这项研究的结果表明，血管内皮是LFN的靶组织，而NO是LFN介导的皮肤血流量增加的效应物。由于改善外周循环通常可以促进人体健康，短期接触LFN可能对健康有益。
