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

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.