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Abstract 845: Acute irradiation exposure induces long-term cardiac adverse effects in the spontaneously hypertensive rat

Radiation-induced heart disease (RIHD) presents a significant challenge in the oncology setting. For instance, patients receiving acute doses of irradiation to the thoracic cavity for Hodgkin9s lymphoma or breast cancer are subject to an elevated risk of RIHD. Excessive oxidative stress, at least in part, is responsible for some of the tissue damage. The ability to monitor and mitigate the long-term cardiac effects of radiation exposure in these populations by modulating oxidative stress has the potential to lead to improved health outcomes. We utilized the spontaneously hypertensive rat (SHR), which has proven a good model for drug-induced cardiotoxicity, to evaluate irradiation-induced heart damage. SHRs were exposed to low, medium, or high doses of full-body irradiation. Necropsy was performed to collect serum and tissue samples at two and four weeks post-irradiation, as well as followed for one year. Four weeks following gamma irradiation, both males and females showed decreased heart mass and decreased whole body mass after exposure to medium and high doses of radiation and these decreases were sustained in the high dose groups after one year. Serum cardiac troponin I and T analysis revealed signs of cardiomyopathy in both the medium and high dose groups at early time points and this signal was sustained in some animals up to one year later. Echocardiography revealed functional changes in cardiac performance including an increase in left ventricular volume at diastole in males and a decrease in left ventricular mass. Low red blood cell count indicated sustained anemic conditions in both males and females receiving the highest dose of irradiation, yet males appeared to be more sensitive. Levels of pro-inflammatory IL-6 were elevated at four weeks in males receiving the high dose. Finally, multiple animals receiving radiation developed spontaneous tumors after one year. We are currently investigating the oxidative stress-mediated molecular mechanisms behind the radiation-induced cardiac damage. Citation Format: Elliot T. Rosen, Dmitry Kryndushkin, Baikuntha Aryal, Yanira Gonzalez, Leena Chehab, Jennifer Dickey, Steven Mog, V Ashutosh Rao. Acute irradiation exposure induces long-term cardiac adverse effects in the spontaneously hypertensive rat [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 845.