Iinuma S, Bachor R, Flotte T, Hasan T
Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston.
J Urol. 1995 Mar;153(3 Pt 1):802-6.
5-Aminolevulinic acid (ALA) is a precursor of heme biosynthesis. In the penultimate step of this biosynthesis, protoporphyrin IX (PpIX), an effective photosensitizer, is generated. In this study, the biodistribution and photodynamic effect of ALA-induced PpIX were investigated in an orthotopic rat bladder tumor model. A quantitative comparison of PpIX biodistribution by extraction and fluorescence spectroscopy following intravenous and intravesical administration of ALA was made. The tumor to normal bladder wall ratio was 2:1 at 4 hours for both delivery modes. Fluorescence microscopy demonstrated predominantly cellular rather than stromal PpIX fluorescence. Phototoxicity, evaluated 4 hours after ALA administration, was light dose-dependent with the most efficient tumor necrosis being observed upon 150 J/cm.2 of 630 nm. irradiation. These data suggest that optimized photodynamic therapy with ALA-induced PpIX may be an alternative treatment for superficial bladder carcinoma.
5-氨基酮戊酸（ALA）是血红素生物合成的前体。在该生物合成的倒数第二步中，会生成有效的光敏剂原卟啉IX（PpIX）。在本研究中，在原位大鼠膀胱肿瘤模型中研究了ALA诱导的PpIX的生物分布和光动力效应。对静脉内和膀胱内给予ALA后通过萃取和荧光光谱法对PpIX生物分布进行了定量比较。两种给药方式下，4小时时肿瘤与正常膀胱壁的比率均为2:1。荧光显微镜检查显示主要是细胞内而非基质中的PpIX荧光。在给予ALA 4小时后评估的光毒性呈光剂量依赖性，在630 nm、150 J/cm²照射时观察到最有效的肿瘤坏死。这些数据表明，用ALA诱导的PpIX进行优化的光动力疗法可能是浅表性膀胱癌的一种替代治疗方法。
