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舒张因子，包括一氧化氮（NO）和内皮源性超极化因子（EDHF），其调节底层平滑肌细胞的张力。目前广泛认为，EDHF与NO一起与小动脉中血管口径的调节有关。然而，目前还没有普遍的协议，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。因此，作为第一步，本研究试图建立一个实时分析测量EDHF介导的血管平滑肌细胞的超极化和舒张。共聚焦荧光显微镜同时测定平滑肌细胞膜电位和收缩-舒张反应的变化。本研究应用细胞膜电位敏感性荧光染料DiBAC_4观察了代谢综合征（MS）模型SHR/NDmcr-cp（SHR-cp）大鼠肠系膜动脉EDHF介导的反应特征，并测定了乙酰胆碱诱导的大鼠肠系膜动脉平滑肌细胞膜电位。使用NIH图像作为血管舒张反应，确定插入血管的导丝之间的距离。我们发现，乙酰胆碱诱导持续和稳定的超极化的存在下，硝基-L-精氨酸甲酯，一氧化氮合酶的抑制剂。此外，与Wistar-Kyoto大鼠相比，SHR-cp大鼠肠系膜动脉的EDHF介导的超极化和血管舒张减少。相反，NO介导的舒张增加SHR-cp大鼠。这些研究结果表明，损害EDHF介导的反应发生在代谢综合征，NO和EDHF之间的备份机制的可能性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.