title: The time course of cutaneous porphyrin photosensitization in the murine ear.
abstract: 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 [14C]Photofrin II in blood, while no relationship between ESR and the level of [14C]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/cm2 of 630-nm light (28 J/cm2/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/cm2, 630 nm, day 9 after injection) showed a mean ESR not significantly different (P less than 0.5) from that for ears which received only a single dose of 88.6 J/cm2 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.
authors.forename: D A
authors.initials: DA
authors.lastname: Bellnier
authors.forename: T J
authors.initials: TJ
authors.lastname: Dougherty
mesh_terms: D000818:Animals; D017323:Dihematoporphyrin Ether; D004423:Ear; D005260:Female; D006415:Hematoporphyrins / Q000494:pharmacology*; D007249:Inflammation; D007834:Lasers; D008027:Light; D051379:Mice; D008813:Mice, Inbred ICR; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D012867:Skin / Q000187:drug effects* / Q000528:radiation effects; D013997:Time Factors
chemical_list: D006415:Hematoporphyrins; D011838:Radiation-Sensitizing Agents; D017323:Dihematoporphyrin Ether