Departamento de Farmacología, Universidad Autónoma de Madrid, Madrid, Spain.
PLoS One. 2011;6(11):e27299. doi: 10.1371/journal.pone.0027299. Epub 2011 Nov 3.
Visfatin, also known as extracellular pre-B-cell colony-enhancing factor (PBEF) and nicotinamide phosphoribosyltransferase (Nampt), is an adipocytokine whose circulating levels are enhanced in metabolic disorders, such as type 2 diabetes mellitus and obesity. Circulating visfatin levels have been positively associated with vascular damage and endothelial dysfunction. Here, we investigated the ability of visfatin to directly impair vascular reactivity in mesenteric microvessels from both male Sprague-Dawley rats and patients undergoing non-urgent, non-septic abdominal surgery. The pre-incubation of rat microvessels with visfatin (50 and 100 ng/mL) did not modify the contractile response to noradrenaline (1 pmol/L to 30 µmol/L), as determined using a small vessel myograph. However, visfatin (10 to 100 ng/mL) concentration-dependently impaired the relaxation to acetylcholine (ACh; 100 pmol/L to 3 µmol/L), without interfering with the endothelium-independent relaxation to sodium nitroprusside (1 nmol/L to 3 µmol/L). In both cultured human umbilical vein endothelial cells and rat microvascular preparations, visfatin (50 ng/mL) stimulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, as determined by lucigenin-derived chemiluminiscence. The relaxation to ACh impaired by visfatin was restored by the NADPH oxidase inhibitor apocynin (10 µmol/L). Additionally, the Nampt inhibitor APO866 (10 mmol/L to 10 µmol/L), but not an insulin receptor-blocking antibody, also prevented the stimulation of NADPH oxidase and the relaxation impairment elicited by visfatin. Accordingly, the product of Nampt activity nicotinamide mononucleotide (100 nmol/L to 1 mmol/L) stimulated endothelial NADPH oxidase activity and concentration-dependently impaired ACh-induced vasorelaxation. In human mesenteric microvessels pre-contracted with 35 mmol/L potassium chloride, the endothelium-dependent vasodilation to bradykinin (1 nmol/L to 3 µmol/L) was equally impaired by visfatin and restored upon co-incubation with APO866. In conclusion, visfatin impairs endothelium-dependent relaxation through a mechanism involving NADPH oxidase stimulation and relying on Nampt enzymatic activity, and therefore arises as a potential new player in the development of endothelial dysfunction.
内脏脂肪素，又称为细胞外前 B 细胞集落增强因子（PBEF）和烟酰胺磷酸核糖转移酶（Nampt），是一种脂肪细胞因子，其在代谢紊乱（如 2 型糖尿病和肥胖症）中循环水平升高。循环内脏脂肪素水平与血管损伤和内皮功能障碍呈正相关。在这里，我们研究了内脏脂肪素直接损害来自雄性 Sprague-Dawley 大鼠和接受非紧急、非脓毒症腹部手术的患者肠系膜微血管血管反应的能力。用小血管描记器测定，内脏脂肪素（50 和 100ng/ml）预孵育大鼠微血管不会改变去甲肾上腺素（1pmol/L 至 30μmol/L）引起的收缩反应。然而，内脏脂肪素（10 至 100ng/ml）浓度依赖性地损害了乙酰胆碱（ACh；100pmol/L 至 3μmol/L）引起的舒张反应，而不干扰内皮非依赖性的硝普钠（1nmol/L 至 3μmol/L）引起的舒张反应。在培养的人脐静脉内皮细胞和大鼠微血管制剂中，内脏脂肪素（50ng/ml）刺激烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶活性，用发光法测定。内脏脂肪素引起的 ACh 舒张受损可被 NADPH 氧化酶抑制剂 apocynin（10μmol/L）恢复。此外，Nampt 抑制剂 APO866（10mmol/L 至 10μmol/L），而不是胰岛素受体阻断抗体，也可防止 NADPH 氧化酶的刺激和内脏脂肪素引起的舒张受损。因此，Nampt 活性产物烟酰胺单核苷酸（100nmol/L 至 1mmol/L）刺激内皮 NADPH 氧化酶活性，并浓度依赖性地损害 ACh 诱导的血管舒张。在用 35mmol/L 氯化钾预收缩的人肠系膜微血管中，内脏脂肪素和 APO866 共孵育后，内皮依赖性的缓激肽（1nmol/L 至 3μmol/L）引起的血管舒张同样受损。总之，内脏脂肪素通过涉及 NADPH 氧化酶刺激和依赖 Nampt 酶活性的机制损害内皮依赖性舒张，因此成为内皮功能障碍发展的一个潜在新因素。
