5-AMINOLEVULINIC-ACID-INDUCED FORMATION OF DIFFERENT PORPHYRINS AND THEIR PHOTOMODIFICATIONS

The relative amounts of 5-aminolaevulinic acid (ALA)-induced hydrophob ic and hydrophilic porphyrins produced in normal mouse tissue and soli d Ehrlich ascites carcinoma in mice were investigated as a function of added glucose, light irradiation and restricted blood flow to the tum our. Protoporphyrin IX (PpIX) is the predominant porphyrin produced fr om exogenous ALA in tissues that have viable mitochondria. However, un der special conditions which seem to be connected with a reduced viabi lity of the mitochondria, the formation of water-soluble porphyrins ca n be observed in vivo. Fluorescence maxima of the water-soluble porphy rins are located in the region between 615 and 625 nm. Irradiation can further lead to the formation of PpIX photoproduct(s), showing a fluo rescence emission band at 676 nm. The photobleaching of PpIX in normal tissue and tumour tissue is different under restricted blood flow. AL A-induced PpIX can be observed in the normal blood stream, and can be linked to a slower photobleaching than in tissue with restricted blood flow.