Drummond Peter D
School of Psychology, Murdoch University, Perth, 6150 Western Australia.
Auton Neurosci. 2006 Jul 30;128(1-2):70-5. doi: 10.1016/j.autneu.2006.03.002. Epub 2006 Apr 19.
Immersion of the hand in painfully cold water induces cutaneous vasodilatation in the temples, more so ipsilaterally than contralaterally. To investigate the mechanism of this response, guanethidine or saline was administered by transcutaneous iontophoresis to a recording site in the temple of ten participants before they immersed one of their hands in ice water. Guanethidine displaces noradrenaline from sympathetic nerve terminals and inhibits sympathetic noradrenergic neurotransmission. Therefore, it was hypothesized that guanethidine pre-treatment would block vasodilatation mediated by release of sympathetic vasoconstrictor tone in cutaneous vessels in the temple. During hand immersion, increases in the amplitude of the pulse waveform detected by laser Doppler flowmetry were greater in the ipsilateral than contralateral temple (86% vs. 34% above baseline, p<0.05), and pre-treatment with guanethidine prevented this asymmetric response (ipsilateral response 21% above baseline and contralateral response 32%, difference not significant). Guanethidine also inhibited ipsilateral increases in cutaneous blood flow during hand immersion in responsive participants. These findings suggest that limb pain inhibited ipsilateral adrenergic vasoconstrictor outflow in the temple. Thus, the findings challenge the concept of the sympathetic nervous system as a "mass action" system that discharges in unison to meet environmental demands. Instead, they suggest that the sympathetic nervous system is highly differentiated, with separate control of discrete reflex pathways on each side of the body.
将手浸入冰冷刺骨的水中会诱发太阳穴处皮肤血管舒张，同侧比异侧更为明显。为了探究这种反应的机制，在十名参与者将一只手浸入冰水中之前，通过经皮离子电渗疗法将胍乙啶或生理盐水施用于其太阳穴处的记录部位。胍乙啶会从交感神经末梢取代去甲肾上腺素，并抑制交感去甲肾上腺素能神经传递。因此，有人推测，预先使用胍乙啶会阻断由太阳穴处皮肤血管中交感缩血管张力释放所介导的血管舒张。在手部浸入过程中，通过激光多普勒血流仪检测到的脉冲波形幅度增加，同侧太阳穴比异侧更为明显（分别比基线高出86%和34%，p<0.05），而预先使用胍乙啶可阻止这种不对称反应（同侧反应比基线高出21%，异侧反应为32%，差异不显著）。胍乙啶还抑制了有反应的参与者在手部浸入过程中同侧皮肤血流量的增加。这些发现表明，肢体疼痛抑制了太阳穴处同侧肾上腺素能缩血管神经流出。因此，这些发现挑战了交感神经系统作为一个“整体作用”系统的概念，即该系统会一致放电以满足环境需求。相反，它们表明交感神经系统具有高度分化性，对身体两侧不同的反射通路进行单独控制。
