Study of photodynamic reactions in human blood

Comparative studies of oxygen consumption, changes of photosensitizer fluor escence, and photodestruction of erythrocytes, and photodestruction of oxyg en transport protein hemoglobin were performed during photodynamic reaction in whole and hemolyzed blood with phthalocyanines, chlorines, porphyrins, and methylene blue photosensitizers in vitro and in selected cases in vivo. The present work deals with the investigation of blood oxygen saturation S O2 and photosensitizer fluorescence during and immediately after light irra diation in the photodynamic therapy process. it has been observed that SO2 behavior strongly correlates with the type of photosensitizer. The decrease of photosensitizer fluorescence (photobleaching) during light irradiation can be followed by the recovery of the photosensitizer fluorescence immedia tely after interruption of the irradiation within 6-8 min. The levels of ph otodestruction of erythrocytes in whole blood and photodestruction of hemog lobin in hemolyzed blood in combination with the above photosensitizers rev eal the influence of photodynamic reactions upon the ability of blood to tr ansport oxygen. Maximal photohemolysis activity has been found with chlorin e p6 photosensitizers. (C) 2000 Society of Photo-Optical instrumentation En gineer. [S1083-3668(00)00303-8].