Sullivan Michelle N, Gonzales Albert L, Pires Paulo W, Bruhl Allison, Leo M Dennis, Li Wencheng, Oulidi Agathe, Boop Frederick A, Feng Yumei, Jaggar Jonathan H, Welsh Donald G, Earley Scott
Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Department of Pharmacology, University of Vermont School of Medicine, Burlington, VT 05405, USA.
Sci Signal. 2015 Jan 6;8(358):ra2. doi: 10.1126/scisignal.2005659.
Reactive oxygen species (ROS) can have divergent effects in cerebral and peripheral circulations. We found that Ca(2+)-permeable transient receptor potential ankyrin 1 (TRPA1) channels were present and colocalized with NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase 2 (NOX2), a major source of ROS, in the endothelium of cerebral arteries but not in other vascular beds. We recorded and characterized ROS-triggered Ca(2+) signals representing Ca(2+) influx through single TRPA1 channels, which we called "TRPA1 sparklets." TRPA1 sparklet activity was low under basal conditions but was stimulated by NOX-generated ROS. Ca(2+) entry during a single TRPA1 sparklet was twice that of a TRPV4 sparklet and ~200 times that of an L-type Ca(2+) channel sparklet. TRPA1 sparklets representing the simultaneous opening of two TRPA1 channels were more common in endothelial cells than in human embryonic kidney (HEK) 293 cells expressing TRPA1. The NOX-induced TRPA1 sparklets activated intermediate-conductance, Ca(2+)-sensitive K(+) channels, resulting in smooth muscle hyperpolarization and vasodilation. NOX-induced activation of TRPA1 sparklets and vasodilation required generation of hydrogen peroxide and lipid-peroxidizing hydroxyl radicals as intermediates. 4-Hydroxy-nonenal, a metabolite of lipid peroxidation, also increased TRPA1 sparklet frequency and dilated cerebral arteries. These data suggest that in the cerebral circulation, lipid peroxidation metabolites generated by ROS activate Ca(2+) influx through TRPA1 channels in the endothelium of cerebral arteries to cause dilation.
活性氧（ROS）在脑循环和外周循环中可产生不同的影响。我们发现，钙通透性瞬时受体电位锚蛋白1（TRPA1）通道存在于脑动脉内皮中，并与NADPH（烟酰胺腺嘌呤二核苷酸磷酸的还原形式）氧化酶2（NOX2，ROS的主要来源）共定位，而在其他血管床中则不存在。我们记录并表征了ROS触发的钙信号，该信号代表通过单个TRPA1通道的钙内流，我们将其称为“TRPA1小火花”。在基础条件下，TRPA1小火花活性较低，但受到NOX产生的ROS刺激。单个TRPA1小火花期间的钙内流是TRPV4小火花的两倍，约为L型钙通道小火花的200倍。代表两个TRPA1通道同时开放的TRPA1小火花在内皮细胞中比在表达TRPA1的人胚肾（HEK）293细胞中更常见。NOX诱导的TRPA1小火花激活了中间电导、钙敏感钾通道，导致平滑肌超极化和血管舒张。NOX诱导的TRPA1小火花激活和血管舒张需要生成过氧化氢和脂质过氧化羟基自由基作为中间产物。脂质过氧化代谢产物4-羟基壬烯醛也增加了TRPA1小火花频率并扩张了脑动脉。这些数据表明，在脑循环中，ROS产生的脂质过氧化代谢产物激活脑动脉内皮中TRPA1通道的钙内流，从而导致血管舒张。
