Khan F, Coffman J D
Peripheral Vascular Section, Evans Memorial Department of Clinical Research, Boston University Medical Center, MA.
Circulation. 1994 Mar;89(3):1183-8. doi: 10.1161/01.cir.89.3.1183.
Vasodilator function was determined in patients with Raynaud's phenomenon during intra-arterial infusions of the endothelium-dependent and -independent vasodilators, methacholine and sodium nitroprusside, respectively. Reactive hyperemia, induced by 5 minutes of arterial occlusion with exercise, was also measured.
Total blood flow was measured in the fingertip and forearm by venous occlusion plethysmography, and blood flow in the forearm skin was determined with laser Doppler flowmetry. Basal fingertip blood flow was not significantly different between control subjects and patients with Raynaud's phenomenon. Infusions of methacholine had no significant effect on fingertip blood flow in control subjects, whereas patients with Raynaud's phenomenon showed a significant increase in fingertip blood flow. Basal total forearm blood flow was significantly lower in patients with Raynaud's phenomenon than in control subjects. Infusions of methacholine and sodium nitroprusside produced dose-related increases in total forearm blood flow that were of similar magnitudes in the two groups, as were the reactive hyperemic responses. Laser Doppler measurements of forearm skin blood flow, however, showed a significantly greater vasodilator response to methacholine in patients with Raynaud's phenomenon than in control subjects. Infusions of sodium nitroprusside produced a relatively small vasodilator response in the skin of the forearm that was smaller than that to methacholine and not significantly different between the two groups.
In Raynaud's phenomenon, a greater vasodilator response to infusions of methacholine in the fingertip, where changes in blood flow mainly reflect those of skin, and in the skin of the forearm may reflect increased responsiveness of cutaneous blood vessels to stimulation of the endothelium. The mechanism involved is unclear but may result from a general abnormality of blood vessels in the skin, which is related to the pathophysiology of cutaneous vasospasm.
分别在动脉内输注内皮依赖性血管舒张剂乙酰甲胆碱和非内皮依赖性血管舒张剂硝普钠期间，测定了雷诺现象患者的血管舒张功能。还测量了通过运动使动脉闭塞5分钟诱导的反应性充血。
通过静脉阻塞体积描记法测量指尖和前臂的总血流量，并用激光多普勒血流仪测定前臂皮肤的血流量。对照组和雷诺现象患者的基础指尖血流量无显著差异。输注乙酰甲胆碱对对照组指尖血流量无显著影响，而雷诺现象患者的指尖血流量显著增加。雷诺现象患者的基础前臂总血流量显著低于对照组。输注乙酰甲胆碱和硝普钠使前臂总血流量呈剂量依赖性增加，两组增加幅度相似，反应性充血反应也是如此。然而，激光多普勒测量前臂皮肤血流量显示，雷诺现象患者对乙酰甲胆碱的血管舒张反应明显大于对照组。输注硝普钠在前臂皮肤产生的血管舒张反应相对较小，小于对乙酰甲胆碱的反应，两组之间无显著差异。
在雷诺现象中，指尖（此处血流量变化主要反映皮肤血流量变化）和前臂皮肤对输注乙酰甲胆碱的血管舒张反应增强，可能反映了皮肤血管对内皮刺激的反应性增加。其涉及的机制尚不清楚，但可能是由于皮肤血管的普遍异常，这与皮肤血管痉挛的病理生理学有关。
