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THE TIME COURSE OF CUTANEOUS PORPHYRIN PHOTOSENSITIZATION IN THE MURINE EAR
Author(s) -
BELLNIER DAVID A.,
DOUGHERTY T. J.
Publication year - 1989
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1989.tb04121.x
Subject(s) - photosensitivity , photobleaching , in vivo , chemistry , porphyrin , fluorescence , edema , erythema , photochemistry , biophysics , medicine , biology , surgery , materials science , optics , optoelectronics , physics , microbiology and biotechnology
This study was designed to investigate the time course of acute cutaneous photosensitivity following administration of Photofrin II using the murine ear swelling response (ESR) as an in vivo end‐point. Ros:(ICR) mice were injected with 5 mg/kg Photofrin II and illuminated 7.5 h to 31 days later with 630‐nm laser light; ESR was measured 24 h after illumination. There was a direct correlation between ESR and the concentration of [ 14 C]Photofrin II in blood, while no relationship between ESR and the level of [ 14 C]Photofrin II in the ear tissue of exsanguinated mice was evident. Photosensitivity in the mouse foot can be suppressed by preexposure to low doses of light via a photochemical destruction of tissue‐bound sensitizer (Boyle and Potter, 1987, Photochem. Photobiol. 46, 997–1001). However, mouse ears pretreated with 84 J/cm 2 of 630‐nm light (28 J/cm 2 /day, given 2, 4 and 6 d after injection), a dose sufficient to reduce porphyrin fluorescence in ear tissue by about 75%, prior to the usual light dose (88.6 J/cm 2 , 630 nm, day 9 after injection) showed a mean ESR not significantly different ( P > 0.5) from that for ears which received only a single dose of 88.6 J/cm 2 on day 9. It is concluded, for this animal model, that circulating porphyrin is the source of photoinduced ear‐tissue edema and that photobleaching of tissue‐bound sensitizer does not attenuate ear‐tissue photosensitivity.