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

以强力霉素(DC：四环素衍生物)为光敏剂，对兔动脉粥样斑块进行光动力治疗(PDT)的可行性进行了实验研究。为了确定PDT可接受的激光功率，我们检测了355 nm激光对兔腹主动脉切除斑块的急性效应。分别用0.5、1、1.5、2、3、6W/cm2的激光照射兔模型，以汽化时间为评价指标，在此基础上，我们决定用0.3/cm2的355 nm激光对兔模型进行光动力治疗。PDT组于静脉注射DC 60 mg/kg后12h，对照组不注射DC，手术暴露腹主动脉形成斑块，然后用355 nm激光直接照射最严重的腹主动脉3min。分别于治疗后1天、1周、2个月处死动物，光镜下观察其病理变化，结果显示PDT治疗后1周出现斑块部分坏死，2个月后斑块缩小或消失。与对照组相比，根据我们的经验，这一过程适合于PDT组，我们认为DC是一种值得临床研究的光敏剂。

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.