MODULATION OF 5-ALA-INDUCED PPIX XENOFLUORESCENCE INTENSITIES OF A MURINE TUMOR AND NONTUMOR TISSUE CULTIVATED ON THE CHORIOALLANTOIC MEMBRANE

Exogenous administration of 6-aminolaevulinic acid (5-ALA), an early p recursor in haem synthesis, induces accumulation of endogenous photo-a ctive porphyrins, particularly protoporphyrin IX (PpIX). Modulation of 5-ALA-induced PpIX-xenofluorescence intensities of a murine tumour an d normal (non-tumour) tissue was studied in vivo on the chorio-allanto ic membrane (CAM) of fertilized chicken embryos. Tumours were grown fr om the murine fibrosarcoma cell line SSK II. Murine 3T3 fibroblasts (c lone A31) were used for cultivating normal tissue. The autofluorescenc e and xenofluorescence intensities of 5-ALA-induced PpIX xenofluoresce nce were compared. After administration of 5-ALA to the CAM inoculated tissues, the SSK II tumours exhibited higher xenofluorescence intensi ties than the 3T3 tissues. Autofluorescence intensities of both types of tissue were not distinguishable. The effects of several biochemical reagents on the xenofluorescence intensities of the fibrosarcoma and fibroblast tissues were investigated. In both tissue types, the intens ities increased after incubation with glucose and antimycin A, while n icotine-adenine-dinucleotide increased the 3T3 fibroblast xenofluoresc ence more than the SSK II fibrosarcoma xenofluorescence. Incubation wi th dimethyl sulphoxide (DMSO) attenuated 5-ALA-induced PpIX xenofluore scence, while oxamic acid attenuated the 3T3 fibroblast xenofluorescen ce more effectively than the xenofluorescence of SSK II fibrosarcoma. Ethanol and 2-iodoacetamide drastically decreased xenofluorescence int ensities in both tumour and normal tissue.