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Proceedings Paper

Modifications In Intratumor Microenvironment With PDT
Author(s): Fred W. Hetzel; Michael Chopp
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Paper Abstract

We have been investigating the dose dependent modification of p02, pH, and phosphate metabolism within tumors subjected to PDT. The system employed in all studies has been the C3H mouse mammary adenocarcinoma tumor model. All tumors were treated at a size of 7.0 ± 0.5 mm (maximum diameter) with biologically defined "doses" ranging from the TCD10 to the TCD90 response level (i.e. from 200 J/cm2 to 600 J/cm2 in this system). The dose of Photofrin II employed in all studies was 12.5 mg/kg (IV) with light treatment 24 hours later (drug kindly supplied by QLT Inc.). All light treatments were at 632 nm (Coherent). Both microelectrodes and 31P NMR spectroscopy (Varian VXR 400) were employed to measure the intralesional values. Results indicate a "dose" dependent reduction in intracellular ATP occurring within 4 hours post treatment. At the TCD90 level, no detectible high energy phosphates are seen within 4 hours following treatment. A similar trend is observed when intralesional p02 is measured with significant decreases seen within 4 hours post treatment. Microelectrode measurements of pH (predominantly extracellular) showed no significant change for up to 72 hours post treatment, independent of "dose". However, some "dose" dependent changes in pH gradient [pH (intracellular) - pH (extracellular)] have been observed.

Paper Details

Date Published: 13 June 1989
PDF: 9 pages
Proc. SPIE 1065, Photodynamic Therapy: Mechanisms, (13 June 1989); doi: 10.1117/12.978002
Show Author Affiliations
Fred W. Hetzel, Henry Ford Hospital (United States)
Michael Chopp, Henry Ford Hospital (United States)

Published in SPIE Proceedings Vol. 1065:
Photodynamic Therapy: Mechanisms
Thomas J. Dougherty, Editor(s)

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