Study of photodynamic reactions in human blood

Abstract

Comparative studies of oxygen consumption, changes of photosensitizer fluorescence, and photodestruction of erythrocytes, and photodestruction of oxygen 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 SO2 and photosensitizer fluorescence during and immediately after light irradiation 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 immediately after interruption of the irradiation within 6-8 min. The levels of photodestruction of erythrocytes in whole blood and photodestruction of hemoglobin in hemolyzed blood in combination with the above photosensitizers reveal the influence of photodynamic reactions upon the ability of blood to transport oxygen. Maximal photohemolysis activity has been found with chlorine p6 photosensitizers.