Institute of Biological Chemistry and Nutrition, University of Hohenheim, Garbenstrasse 28, 70593 Stuttgart, Germany.
Free Radic Biol Med. 2010 Jan 1;48(1):153-60. doi: 10.1016/j.freeradbiomed.2009.10.036. Epub 2009 Oct 21.
Infrared radiation is a substantial part of the solar energy output reaching the earth surface. Therefore, exposure of humans to infrared radiation is common. However, whether and how infrared (IR) or infrared A acts on human skin cells is still under debate. Recently the generation of reactive oxygen species by water-filtered infrared A (wIRA) irradiation was postulated. wIRA shows a spectral distribution similar to that of solar irradiation at the earth's surface. Thus, the need for protection of human skin from both solar- and artificially generated infrared A irradiation was concluded. Here we demonstrate that in human dermal fibroblasts this reactive oxygen species generation is dependent on heat formation by infrared A and can be reproduced by thermal exposure. On the other hand wIRA irradiation had no detectable effect if the temperature in the cells was kept constant, even if irradiance exceeded the extraterrestrial solar irradiance in the IR range by a factor of about 4 and the maximum at noontime in the tropics by a factor up to about 6. This could be demonstrated by the measurement of oxidant formation using H(2)DCFDA and the determination of protein carbonyls. In additional experiments we could show that during thermal exposure the mitochondria contribute significantly to oxidant production. Further experiments revealed that the major absorbance of infrared is due to absorption of the energy by cellular water.
红外辐射是到达地球表面的太阳能输出的重要组成部分。因此，人类暴露于红外辐射下是很常见的。然而，红外（IR）或红外 A 是否以及如何作用于人体皮肤细胞仍存在争议。最近有人提出，水过滤的红外 A（wIRA）辐照会产生活性氧物质。wIRA 显示出与地球表面太阳辐射相似的光谱分布。因此，人们得出结论，需要保护人体皮肤免受太阳和人工产生的红外 A 辐射的伤害。在这里，我们证明在人类真皮成纤维细胞中，这种活性氧物质的产生依赖于红外 A 产生的热量，并且可以通过热暴露来重现。另一方面，如果细胞内的温度保持不变，wIRA 辐射即使辐照度在红外范围内超过了地球外的太阳辐照度的 4 倍左右，并且在热带地区的中午甚至超过了 6 倍，也不会产生可检测的效果。这可以通过使用 H(2)DCFDA 测量氧化剂的形成和测定蛋白质羰基来证明。在额外的实验中，我们可以证明在热暴露期间，线粒体对氧化剂的产生有很大的贡献。进一步的实验表明，红外的主要吸收是由于细胞水吸收能量所致。
