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Abstract #2710

Captopril and S-Nitrosocaptopril as Potent Radiosensitizers: Comparative MR Study and Underlying Mechanisms.

Benedicte F. Jordan1, Julie Peeterbroeck1, Oussama Karroum1, Caroline Diepart1, Julie Magat1, Vincent Gregoire2, Bernard Gallez1

1Biomedical Magnetic Resoncance Unit, Universite Catholique de Louvain, Brussels, Belgium; 2IMRE, Universite Catholique de Louvain

EPR and 19F-MRI oximetry were used to monitor acute changes in tumor hemodynamics after administration of potential NO-mediated radiation co-treatments. For this purpose, S-nitrosocaptopril, a converting enzyme inhibitor with vasodilatory properties combined to a nitric oxide donor, was tested in experimental tumors. Tumor oxygenation was significantly increased 30 minutes after administration of the co-treatment. This effect was the result of an increase in tumor blood flow along with a decrease in tumor oxygen consumption by tumor cells. This oxygen effect contributed to the increase in efficacy of radiation therapy with 10Gy of X-rays, an effect that was not observed with captopril alone.