Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Department of Mechanical Engineering, Graduate School of Engineering, Kyushu University, Fukuoka, Japan.
J Physiol Anthropol. 2020 Nov 23;39(1):37. doi: 10.1186/s40101-020-00248-4.
Cold-induced vasodilation (CIVD) is known to be influenced by the ambient temperature. Frequency analysis of blood flow provides information on physiological regulation of the cardiovascular system, such as myogenic, neurogenic, endothelial nitric oxide (NO) dependent, and NO-independent activities. In this study, we hypothesized that the major origin of CIVD occurs prior to the CIVD event and investigated finger skin blood flow during the initial stage of CIVD at different ambient temperatures using frequency analysis.
Eighteen healthy volunteers immersed their fingers in 5 °C water at air temperatures of 20 °C and 25 °C. Finger skin blood flow was measured using laser Doppler flowmetry and analyzed using Morlet mother wavelet. We defined the time when the rate of blood flow increased dramatically as the onset of CIVD, and defined three phases as the periods from the onset of cooling to minimum blood flow (vasoconstriction), from minimum blood flow to the onset of CIVD (prior to CIVD), and from the onset of CIVD to maximum blood flow (CIVD).
The increment ratio of blood flow at CIVD was significantly higher at 20 °C air temperature. In particular, at 20 °C air temperature, arteriovenous anastomoses (AVAs) might be closed at baseline, as finger skin temperature was much lower than at 25 °C air temperature, and endothelial NO-independent activity was significantly higher and neurogenic activity significantly lower during vasoconstriction than at baseline. Additionally, the differences in both activities between vasoconstriction and prior to CIVD were significant. On the other hand, there were no significant differences in endothelial NO-dependent activity between baseline and all phases at both air temperatures.
Our results indicated that the increase of endothelial NO-independent activity and the decrease of neurogenic activity may contribute to the high increment ratio of blood flow at CIVD at 20 °C air temperature.
冷诱导血管舒张（CIVD）已知受环境温度影响。血流的频率分析提供了有关心血管系统生理调节的信息，例如肌源性、神经源性、内皮一氧化氮（NO）依赖性和非 NO 依赖性活动。在这项研究中，我们假设 CIVD 的主要起源发生在 CIVD 事件之前，并在不同的环境温度下使用频率分析研究了 CIVD 初始阶段手指皮肤血流。
18 名健康志愿者将手指浸入 5°C 水中，环境温度分别为 20°C 和 25°C。使用激光多普勒流量仪测量手指皮肤血流，并使用 Morlet 母波进行分析。我们将血流率急剧增加的时间定义为 CIVD 的发作时间，并将三个阶段定义为从冷却开始到血流最低（血管收缩）、从血流最低到 CIVD 开始（CIVD 之前）和从 CIVD 开始到血流最高（CIVD）的时间段。
CIVD 时血流的增量比在 20°C 空气温度下显着更高。特别是在 20°C 空气温度下，由于手指皮肤温度远低于 25°C 空气温度，因此可能在基线时已经关闭动静脉吻合（AVA），并且在血管收缩期间内皮 NO 非依赖性活动显着更高，神经源性活动显着更低，与基线相比。此外，在收缩期和 CIVD 之前，两种活动之间的差异均具有统计学意义。另一方面，在两种空气温度下，内皮 NO 依赖性活动在基线和所有阶段之间均无显着差异。
我们的结果表明，内皮 NO 非依赖性活动的增加和神经源性活动的减少可能导致 20°C 空气温度下 CIVD 时血流的高增量比。
