CANINE BLADDER RESPONSE TO RED AND GREEN LIGHT WHOLE BLADDER PHOTODYNAMIC THERAPY

A normal canine bladder model was used to compare the effects of red a nd green light whole bladder photodynamic therapy (PDT). Eighteen dogs were treated with Photofrin 1 mg/kg and whole bladder irradiation wit h red or green light at doses ranging from 20 to 60 J/cm2. Toxicity wa s assessed using cystometry, cystoscopy, and histopathology. Green lig ht produced more significant vesical toxicity than red light, and this toxcity tended to vary with the light dose administered. Whole bladde r PDT with green light at doses greater than 20 J/cm2 resulted in perm anent reductions in bladder capacity. Conversely, a green light dose o f 20 J/cm2 and red light doses ranging from 20 to 60 J/cm2 did not pro duce any significant permanent reductions in bladder capacity. Thus, w hile green light may be more toxic to the bladder than red light, ther e are distinct combinations of red or green light and Photofrin which can be used in the canine bladder to achieve mucosal degradation witho ut causing permanent vesical dysfunction.