Yamaguchi Yuji, Ikemura Tsukasa, Kashima Hideaki, Hayashi Naoyuki
Graduate School of Human-Environment Studies, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan.
Eur J Appl Physiol. 2015 Mar;115(3):619-25. doi: 10.1007/s00421-014-3049-9. Epub 2014 Nov 16.
Visual stimulation increases the blood flow in the posterior cerebral artery (PCA), which supplies blood to the visual cortex by neurovascular coupling (NVC). Relative contributions of vasodilatation and pressor response on NVC during dynamic exercise are still unknown.
We measured the blood flow velocity in the PCA (PCAv) by transcranial Doppler ultrasound flowmetry during rest and exercise in 14 healthy males while they performed 12-min submaximal leg-cycle exercises at mild-, moderate-, and high-intensity, which corresponded to heart rates of 120, 140, and 160 bpm, respectively. NVC was estimated as the relative change in PCAv from 20 s eye-closing to the peak response during 40 s looking at a reversed checkerboard. Conductance index was calculated for evaluating vasodilatation as pressure divided by blood flow.
In response to visual stimulation, a magnitude of vasodilatation was significantly decreased under the moderate-intensity, while pressor response was significantly suppressed under the high-intensity exercises, compared with the control condition. Conversely, peak response to visual stimulation in PCAv was not affected by exercise intensity though relative and absolute responses were significantly lower in the moderate- and high-intensity exercises than the control.
It is suggested that the contributions of pressor response and vasodilatation were modified by exercise intensity, partly playing a role for stabilizing the peak response of PCAv with visual stimulation during dynamic exercise.
视觉刺激可增加大脑后动脉（PCA）的血流量，该动脉通过神经血管耦合（NVC）为视觉皮层供血。动态运动期间血管舒张和压力反应对NVC的相对贡献仍不清楚。
我们在14名健康男性休息和运动期间，通过经颅多普勒超声血流仪测量了PCA的血流速度（PCAv），他们进行了12分钟的次最大腿部循环运动，运动强度分别为轻度、中度和高强度，对应的心率分别为120、140和160次/分钟。NVC被估计为从闭眼20秒到观看反转棋盘40秒内PCAv的相对变化。计算传导指数以评估血管舒张，即压力除以血流量。
与对照条件相比，在中等强度运动下，视觉刺激引起的血管舒张幅度显著降低，而在高强度运动下，压力反应显著受到抑制。相反，尽管在中等强度和高强度运动中，PCAv对视觉刺激的峰值反应相对和绝对反应均显著低于对照，但不受运动强度的影响。
提示压力反应和血管舒张的贡献受运动强度的影响，部分作用是在动态运动期间通过视觉刺激稳定PCAv的峰值反应。
