Zhang D X, Zou A P, Li P L
Department of Pharmacology, Medical College of Wisconsin, Milwaukee, USA.
Circ Res. 2001 Apr 27;88(8):824-31. doi: 10.1161/hh0801.089604.
Ceramide serves as a second messenger in a variety of mammalian cells. Little is known regarding the role of ceramide in the regulation of vascular endothelial function. The present study was designed to determine whether ceramide affects endothelium-dependent vasodilation in coronary arteries and to explore the mechanism of action of ceramide. In isolated and pressurized small bovine coronary arteries, cell-permeable C(2)-ceramide (10(-)(5) mol/L) markedly attenuated vasodilator responses to bradykinin and A23187 (by 40% and 60%, respectively). In the presence of K(G)-nitro-L-arginine methyl ester, ceramide produced no further inhibition on the vasodilation induced by these vasodilators. Ceramide had no effect on DETA NONOate-induced vasodilation. By use of a fluorescence NO indicator (4,5-diaminofluorescein diacetate), intracellular NO was measured in the endothelium of freshly isolated small coronary arteries. It was found that ceramide significantly inhibited bradykinin-induced NO increase within endothelial cells. However, it had no effect on the activity of arterial or endothelial NO synthase. Pretreatment of the arteries with sodium dihydroxybenzene disulfonate (Tiron, 10(-)(3) mol/L), a cell-permeable superoxide scavenger, or polyethylene glycol superoxide dismutase (100 U/mL) largely restored the inhibitory effects of ceramide on the vasodilation and NO increase induced by bradykinin or A23187. Moreover, ceramide time-dependently increased intracellular superoxide (O(2)(-. )) in the endothelium, as measured by a fluorescent O(2)(-. )indicator, dihydroethidium. These results demonstrate that ceramide inhibits endothelium-dependent vasodilation in small coronary arteries by decreasing NO in vascular endothelial cells and that this decrease in NO is associated with increased O(2)(-. ) but not with the inhibition of NO synthase activity within these cells.
神经酰胺在多种哺乳动物细胞中作为第二信使发挥作用。关于神经酰胺在调节血管内皮功能中的作用，人们了解甚少。本研究旨在确定神经酰胺是否影响冠状动脉中内皮依赖性血管舒张，并探讨神经酰胺的作用机制。在离体并加压的小牛冠状动脉中，细胞可渗透的C(2)-神经酰胺（10⁻⁵ mol/L）显著减弱了对缓激肽和A23187的血管舒张反应（分别降低了40%和60%）。在存在K(G)-硝基-L-精氨酸甲酯的情况下，神经酰胺对这些血管舒张剂诱导的血管舒张没有进一步的抑制作用。神经酰胺对DETA NONOate诱导的血管舒张没有影响。通过使用荧光NO指示剂（4,5-二氨基荧光素二乙酸酯），在新鲜分离的小冠状动脉内皮中测量细胞内NO。发现神经酰胺显著抑制内皮细胞内缓激肽诱导的NO增加。然而，它对动脉或内皮型NO合酶的活性没有影响。用二羟基苯二磺酸钠（Tiron，10⁻³ mol/L）（一种细胞可渗透的超氧化物清除剂）或聚乙二醇超氧化物歧化酶（100 U/mL）预处理动脉，在很大程度上恢复了神经酰胺对缓激肽或A23187诱导的血管舒张和NO增加的抑制作用。此外，通过荧光超氧化物指示剂二氢乙啶测量，神经酰胺能使内皮中的细胞内超氧化物（O₂⁻）随时间增加。这些结果表明，神经酰胺通过降低血管内皮细胞中的NO来抑制小冠状动脉中的内皮依赖性血管舒张，并且这种NO的降低与O₂⁻增加有关，而与这些细胞内NO合酶活性的抑制无关。
