Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA.
Photochem Photobiol. 2010 Mar-Apr;86(2):389-96. doi: 10.1111/j.1751-1097.2009.00682.x. Epub 2010 Jan 13.
Elevation of nitric oxide (NO*) can either promote or inhibit ultraviolet B light (UVB)-induced apoptosis. In this study, we determined real-time concentration of NO* and peroxynitrite (ONOO(-)) and their role in regulation of membrane integrity and apoptosis. Nanosensors (diameter 300-500 nm) were used for direct in situ simultaneous measurements of NO* and ONOO(-) generated by UVB in cultured keratinocytes and mice epidermis. An exposure of keratinocytes to UVB immediately generated ONOO(-) at maximal concentration of 190 nm followed by NO() release with a maximal concentration of 91 nm. The kinetics of UVB-induced NO/ONOO(-) was in contrast to cNOS agonist stimulated NO*/ONOO(-) from keratinocytes. After stimulating cNOS by calcium ionophore (CaI), NO* release from keratinocytes was followed by ONOO(-) production. The [NO*] to [ONOO(-)] ratio generated by UVB decreased below 0.5 indicating a serious imbalance between cytoprotective NO* and cytotoxic ONOO(-)-a main component of nitroxidative stress. The NO*/ONOO(-) imbalance increased membrane damage and cell apoptosis was partially reversed in the presence of free radical scavenger. The results suggest that UVB-induced and cNOS-produced NO* is rapidly scavenged by photolytically and enzymatically generated superoxide (O(2) (-)) to produce high levels of ONOO(-), which enhances oxidative injury and apoptosis of the irradiated cells.
一氧化氮（NO*）水平的升高既可以促进也可以抑制紫外线 B 光（UVB）诱导的细胞凋亡。在本研究中，我们测定了 NO和过氧亚硝酸盐（ONOO(-)）的实时浓度及其在调节细胞膜完整性和细胞凋亡中的作用。纳米传感器（直径 300-500nm）用于直接原位同时测量 UVB 在培养的角质细胞和小鼠表皮中产生的 NO和 ONOO(-)。角质细胞暴露于 UVB 后，立即产生最大浓度为 190nm 的 ONOO(-)，随后释放最大浓度为 91nm 的 NO*。UVB 诱导的 NO*/ONOO(-)的动力学与钙载体（CaI）刺激角质细胞产生的 nNOS 激动剂刺激的 NO*/ONOO(-)不同。钙载体刺激 nNOS 后，NO从角质细胞中释放，随后产生 ONOO(-)。UVB 产生的 [NO]与 [ONOO(-)]的比值降至 0.5 以下，表明细胞保护的 NO和细胞毒性的 ONOO(-)之间严重失衡-这是氮氧化应激的主要组成部分。NO/ONOO(-)失衡增加了膜损伤，并且在自由基清除剂存在下，细胞凋亡部分逆转。结果表明，UVB 诱导的和 nNOS 产生的 NO*被光解和酶促产生的超氧阴离子（O(2) (-)）迅速清除，产生高水平的 ONOO(-)，这增强了辐照细胞的氧化损伤和凋亡。
