Protoporphyrin-IX Distribution and Photodynamic Effect in Rat Oesophagus after Aminolevulinic Acid Administration

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Abstract
Background: Photodynamic therapy (PDT) is a method for local and selective tumour destruction achieved by the action of light on a photosensitizing drug. Methods: We investigated the distribution of 5-amino-laevulinic acid (ALA)-induced protoporphyrin-IX fluorescence in rat oesophagus by fluorescence microscopic examination and then studied the effects of PDT. Results: The highest level of fluorescence was achieved in the mucosa after 4 h of 300 mg/kg ALA administration. A clear difference in fluorescence between mucosa and muscularis was found in all samples except those taken 24 h after ALA administration. PDT with ALA caused destruction of the mucosal and, partly, submucosal layers of the oesophagus without damaging the muscularis layer. Conclusions: According to our results with microscopic fluorescence kinetics and the preliminary results of PDT, selective destruction of the superficial layer of the rat oesophagus is achieved with PDT after ALA administration.