Chloroaluminum sulfonated phthalocyanine versus dihematoporphyrin ether: Early vascular events in the rat window chamber

The development of a simple and well-tolerated rat window chamber has allowed direct comparison of the vascular effects of two photosensitizers, chlo- roaluminum sulfonated phthalocyanine (CASP) and dihematoporphyrin ether (DHE).CASP and DHE were given 4 days after the implantation of the window chamber. Photodynamic therapy (PDT) with CASP was performed 24 hours after intravenous injection (10 mg/kg) with light at 675 nm (power density 200 mW/cm2, incident energy 100 J). DHE was given in a similar fashion (5 mg/kg intraperitoneally; light at 630 nm with matching power density and energy settings 24 hours after injection).Using videomicroscopic and integrating sphere measurements, marked differences were noted in the vascular effects of these photosensitizers. DHE caused immediate hemorrhage and disruption of the postcapillary venules, while CASP induced vascular spasm starting 4 hours after the completion of PDT. Forty-eight hours after PDT, both systems demonstrated a loss of chamber-induced neovascularization.