Deptartment of Physical Therapy, School of Allied Health Professions, Loma Linda University, CA, USA.
Med Sci Monit. 2013 Aug 5;19:641-7. doi: 10.12659/MSM.889278.
Vitamin D is a modulator of the immune system. There is some limited evidence that it also increases local blood flow in response to stress.
In the present study, we examined 20 age matched subjects; 10 whom were from India and 10 Caucasians from the United States. Subjects were administered 4000 IU of Vitamin D3 for 3 weeks at breakfast. The function of the endothelial cells was evaluated in 2 ways; first, the response to 4 minutes of vascular occlusion was measured with a laser Doppler flow meter and second, the blood flow response to local heat at 42°C for 6 minutes.
The results of the experiments showed that, as reported previously, the endothelial function in people from India was less than their Caucasian counterparts. The blood flow response to heat was reduced after 3 weeks administration of vitamin D in both groups and the response to vascular occlusion in the Caucasian group. But there was only a 20% reduction in the blood flow response to heat in the Caucasian group and a 50% reduction in the group from India.
Thus acute doses of vitamin D may increase vascular tone and reduce blood flow to tissue during stressors. Dosages administered for a longer duration may have beneficial effects on endothelial function but this was not examined here.
维生素 D 是免疫系统的调节剂。有一些有限的证据表明，它也可以增加局部血流量以应对压力。
在本研究中，我们检查了 20 名年龄匹配的受试者；其中 10 名来自印度，10 名来自美国的白种人。受试者在早餐时服用 4000IU 的维生素 D3，持续 3 周。内皮细胞的功能通过两种方式进行评估；首先，使用激光多普勒流量计测量 4 分钟血管闭塞的反应，其次，测量 42°C 局部热 6 分钟的血流反应。
实验结果表明，正如之前报道的那样，来自印度的人的内皮功能比他们的白种人对应者差。在两组中，维生素 D 给药 3 周后，对热的血流反应均降低，而白种人组对血管闭塞的反应也降低。但是，白种人组对热的血流反应仅降低了 20%，而印度组则降低了 50%。
因此，急性剂量的维生素 D 可能会增加血管张力并减少应激时组织的血流量。更长时间给予的剂量可能对内皮功能有益，但这里没有检查。
