The endothelium-derived hyperpolarizing factor (EDHF) to maintain vascular tone actually exists

血管内皮细胞合成并释放各种血管松弛因子，包括一氧化氮（NO）和内皮源性超极化因子（EDHF），它们调节底层平滑肌细胞的张力。目前已被广泛接受的是EDHF与NO一起与小动脉血管口径的调节有关。然而，对于EDHF的性质、介导EDHF介导的超极化的细胞过程或其生理和病理生理意义，目前还没有普遍的共识。因此，作为第一步，本研究试图建立一种实时分析方法来测量edhf介导的血管平滑肌细胞的超极化和松弛。同时用共聚焦荧光显微镜观察平滑肌细胞膜电位和收缩舒张反应的变化。这些发现被用于研究代谢综合征大鼠模型SHR/NDmcr-cp （SHR-cp）大鼠肠系膜动脉edhf介导的反应特征。采用膜电位敏感荧光染料DiBAC_4对大鼠肠系膜动脉平滑肌细胞膜电位进行观察，测定乙酰胆碱诱导的平滑肌细胞膜电位。使用NIH图像作为血管松弛反应来确定插入血管的导线之间的距离。我们发现乙酰胆碱在NO合成酶抑制剂硝基- l -精氨酸甲酯存在的情况下诱导持续稳定的超极化。此外，与Wistar-Kyoto大鼠相比，SHR-cp大鼠edhf介导的肠系膜动脉超极化和血管舒张减少。相反，shrr -cp大鼠no介导的松弛增强。这些发现表明，EDHF介导的反应损伤发生在代谢综合征中，并且NO和EDHF之间可能存在备份机制，具有重要的病理生理意义。

Vascular endothelial cells synthesize and release various vasorelaxing factors, including nitric oxide (NO) and an endothelium-derived hyperpolarizing factor (EDHF), which regulate the tonus of underlying smooth muscle cells. It is now widely accepted that EDHF, together with NO, is associated with regulation of the vascular caliber in small arteries. However, there is not yet universal agreement on the nature of EDHF, the cellular processes that mediate EDHF-mediated hyperpolarization, or its physiological and pathophysiological significance. Thus, as a first step, the present study attempted to establish a real-time analysis for measurement of EDHF-mediated hyperpolarization and relaxation in vascular smooth muscle cells. Changes of the smooth muscle cell membrane potential and contraction-relaxation response were coincidentally determined using confocal fluorescence microscopy. The findings were used to examine the characteristics of the EDHF-mediated response in mesenteric arteries of SHR/NDmcr-cp (SHR-cp) rats, a rat model of metabolic syndrome.To measure the smooth muscle cell membrane potential induced by acetylcholine in rat mesenteric arteries, they were visualized using a membrane potential-sensitive fluorescence dye, DiBAC_4. The distance between wires inserted into a vessel was determined using the NIH image as a vasorelaxation response. We found that acetylcholine induced sustained and stable hyperpolarization in the presence of nitro-L-arginine methyl ester, an inhibitor of NO synthase. Furthermore, EDHF-mediated hyperpolarization and vasorelaxation in mesenteric arteries of SHR-cp rats were reduced compared with those of Wistar-Kyoto rats. In contrast, NO-mediated relaxation was increased in SHR-cp rats. These findings suggest that impairment of the EDHF-mediated response occurs in metabolic syndrome, and that the possibility of a back-up mechanism between NO and EDHF has important pathophysiological implications.