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Analysis of the Heterogeneity of pO 2 Dynamics During Photodynamic Therapy with Verteporfin ¶
Author(s) -
Pogue Brian W.,
Braun Rod D.,
Lanzen Jennifer L.,
Erickson Christian,
Dewhirst Mark W.
Publication year - 2001
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 - 10.1562/0031-8655(2001)0740700aothop2.0.co2
Subject(s) - verteporfin , photodynamic therapy , blood flow , mammary carcinoma , chemistry , oxygen , medicine , cardiology , macular degeneration , carcinoma , ophthalmology , organic chemistry , choroidal neovascularization
Photodynamic therapy (PDT) with verteporfin provides a reliable way to destroy malignant tissues. Changes in the blood flow and oxygen partial pressure (pO 2 ) during verteporfin‐PDT were studied here in the tumor tissue of the rat mammary R3230Ac carcinoma model. Oxygen microelectrodes (6–12 μm tip diameter) were used to measure the transients locally within tumors during intravenous injection of 1.0 mg/kg verteporfin followed by irradiation 15 min later with 690 nm light at 200 mW/cm 2 , for a cumulative dose of 144 J/cm 2 . The observed changes in pO 2 were heterogeneous and there was a difference in the response of low‐pO 2 regions relative to higher‐pO 2 regions. The change in pO 2 in hypoxic tissue regions (pO 2 < 8 mmHg) had acute pO 2 loss after treatment, whereas the response in regions of higher pO 2 (>8 mm Hg) was more heterogeneous with some areas maintaining their pO 2 value after treatment was completed. Blood flow measurements taken on a subset of the animals indicated a significant loss in flow during the initial light delivery that remained low after treatment, indicating some vascular stasis. The results suggest that hypoxic or poorly perfused vessels may be more susceptible to acute stasis than normoxic vessels in this treatment protocol.