An Experimental Study of Photodynamic Therapy Using Doxycycline Derivertives on Rabbit Atherosclerosis Model

采用多西环素（Dc：四环素衍生物）作为光敏剂，实验评价了光动力疗法（PDT）治疗兔动脉粥样硬化斑块的可能性。为了确定PDT的可接受激光功率，我们之前研究了355nm激光对兔腹主动脉切除斑块的急性影响。分别在0.5、1、1.5、2、3、6W/cm^2的功率下对激光进行直流和无直流处理，并以蒸发时间来评价效果。基于这一结果，我们决定用0.3/cm^2的355nm激光源对兔模型进行PDT试验。注射60mg/kg Dc后12 h的PDT组和未注射Dc的对照组均行诱导斑块的腹主动脉手术暴露，然后向最严重的腹主动脉直接照射355nm激光3分钟。分别于治疗后1天、1周和2个月处死，显微镜下观察病理变化。结果，PDT的影响表现为治疗后1周斑块出现部分坏死，治疗后2个月斑块减少或消失。根据我们的经验，与对照组相比，这一过程适合于PDT组，我们认为Dc是值得临床研究的光敏剂之一。

Using doxycycline(Dc : tetracycline derivertive) as a photosensitizer, the authers experimentally evaluated the possibility of photodynamic therapy(PDT) for atheromatous plaques on rabbit's models.In order to define the acceptable laser power for PDT, we examined previously the acute effects of 355nm laser for resected plaques that induced in rabbit's abdominal aorta. Treated with or without Dc, the laser was radiated in the power of 0.5, 1, 1.5, 2, 3 or 6W/cm^2, and the effect was evaluated as vapolizetion time.Based on this result, we decided to try the PDT to the rabbit's models with 0.3/cm^2 of 355nm laser source. The PDT group that was 12 hours after the infusion of 60mg/kg Dc and control group without Dc underwent surgical exposure of their abdominal aortas in which plaques were induced, then the 355nm laser was radiated for 3 minutes directly to the most severe one. They were killed at 1 day, 1 week and 2 months after the treatment, and their pathological changes were examined microscopically.In result, the effects of PDT were presented as some necrosis of the plaques at 1 week after the treatment, and reduction or disappearance of them at 2 months after. Compared to the control group, this process were proper to the PDT group in our experience, and we thought that Dc was one of the photosensitizers which were worth to investigate for clinical use.