PROTOPORPHYRIN-IX DISTRIBUTION AND PHOTODYNAMIC EFFECT IN RAT ESOPHAGUS AFTER AMINOLEVULINIC ACID ADMINISTRATION

Background: Photodynamic therapy (PDT) is a method for local and selec tive tumour destruction achieved by the action of light on a photosens itizing drug. Methods: We investigated the distribution of 5-aminolaev ulinic acid (ALA)-induced protoporphyrin-IX fluorescence in rat oesoph agus by fluorescence microscopic examination and then studied the effe cts of PDT. Results: The highest level of fluorescence was achieved in the mucosa after 4 h of 300 mg/kg ALA administration. A dear differen ce in fluorescence between mucosa and muscularis was found in all samp les except those taken 24 h after ALA administration. PDT with ALA cau sed destruction of the mucosal and, partly, submucosal layers of the o esophagus without damaging the muscularis layer. Conclusions: Accordin g to our results with microscopic fluorescence kinetics and the prelim inary results of PDT, selective destruction of the superficial layer o f the rat oesophagus is achieved with PDT after ALA administration.